You have a DH problem
Don't "gently poke" at this with him. Sit down, no distractions and say "we need to talk about SD and our living situation". Instead of trying to get her to get a job, try to create a plan with him. Are you guys able to agree to a three month plan? She has three months to get a job and get her own place or enroll in school, or start paying rent...something you think you can live with. You need to explain to DH that you don't want a roommate, that this is your home and she is an adult. If you able to agree on a plan, sit her down, write the plan out and make everyone sign. Here's the catch, there has to be some consequences if he doesn't follow the plan when it's time. Are you willing to move out? Is there a financial consequence you can implement? Change the locks? Stop being gentle. It's time to start drawing a line. Your problem isn't your SD, it's your DH and his coddling of his daughter. If he doesn't want to talk or make a plan, or gets defensive, get ready to move out.

You know your DH is crippling her, right? When is she ever going to learn life skills? She either needs to get a job or go to school. Or live with you forever.

She can't feel good about herself if all her friends are working and moving forward and maturing. Next comes self medication because she feels so bad about herself. Then you have a substance abuse problem on top of laziness.

Nothing good will come from allowing a teenager to sit around and mooch off of daddy. And this IS all about your DH -- he, for some reason, wants to keep her dependent on him. Oh, he'll deny it. but the evidence is right in front of your eyes.

Why such different rules between DH's kids? He's good with his son doing dishes and cleaning his bedroom but , nope, not his daughter. WTF?

Unless SD gets higher education or specialized training she's pretty much limited in what she will ever be able to work at. Low wages for sure. Why no motivation? Considering her friends work, I'm surprised SD doesn't want pocket money and to be able to go out and partake in the activities they can do. Oh, right, Dad gives her cash.

I don't get it. Did SD do well in school?

Yes, she most probably will, mootch off you and hubby, unless a PLAN is created, implemented and followed through with consequences if not.
Don't pressure SD my A$$! Because poor special snowflake cant handle a real job with real responsibilities? First off, take control of your household - get some chores done. Personally I have seen removal of bedroom door work wonders for keeping room clean.

I have the same problem. BUT SD17 hasn't turned 18 yet and still needs to graduate HS (this summer we shall see) However, she has no job, no license, and her phone bill hasn't been paid. So its going to be an uphill trek.

Your DH needs to read her the riot act pronto. Or you need to create an escape hatch from the sitch. Do you REALLY want her around for another year, or two or three?

Really?

I agree SD is not the problem DH is....

Now take control and tell them SD, you have 3 months to find a paying job to start paying rent, in the mean time you will clean the house and dishes etc, 3 months and then I will move you out of the house... give DH a bitch look and say and if you do not stop enabling her you are moving with her understood.

Turn around and walk away, never say anything again, after 3 months you simply pack her shit, leave it out and cut her phone.

The "I don't know" comment from SD seems to speak volumes ... Depression, learned helplessness, or merely a sense of being lost,... perhaps SD needs help to create a life plan. Counselor for depression? Practical coaching from you and DH regarding how to function in the world? SD does not sound as if she has any future plan and no one to help her create a tangible one. Focusing on the little things like laundry and house rules tends to ignore the elephant in the living room which involves launching a viable humanoid.

BTW: at 18, I did not have a life plan. I had my belongings in a black trash bag. Looking back, I wish that I had a cognisant adult to help me make a step-by-step plan because I felt overwhelmed.

We solved this problem by taking the kid's house key, turning off the internet and cable TV when we left for work each morning, and giving him a chore list. If he failed to get his chores done by the time his mom and I got home from work in the evening... he was on the curb when we left for work the next AM. He was left here with no food, no water (except the garden hose), and he sat their all day until we got home or he could figure something else out.

It only took 2-3 tests of our commitment to this strategy for him to gain clarity and not be locked out of the house for the work day. One of the times he tested it was very hot, one it was pretty cold, and the third I don't recall the weather but he learned that if he was to live in our comfortable home he had to step up.

To prevent him being comfortable we added increasingly more tasks to his chore list. He scrubbed, cleaned, wiped, swept, vacuumed, mopped, dusted, washed, folded, scrapped, sanded, painted, mowed, weeded, edged, mulched, trimmed, sliced, diced, chopped, cut, prepped, brazed, broiled, roasted, sautéed, seasoned, plated, served, polished and put away, etc.... until he finally gained clarity and enlisted in the USAF and reported for Basic 8mos after his 18th birthday.

"I don't know" is the kiss of death for any relationship..... including the parent child relationship once the child is no longer a young child. Time for her to start to gain clarity that "I don't know" is no longer acceptable. She is not a kid. She is ostensibly an adult. Time for her to learn adult lessons. Shut down the cable TV and internet when you and DH leave for work every morning. Cancel her cellphone plan and put her on a pre-paid plan with very limited minutes and if she fails to do her ever increasing chore list... she gets cut off from all external communication capability unless she gets her ass out and gets a job.

Lather, rinse, repeat... it works. Try it.

This is the thing... unless your DH is ready, willing, and able to deal with his kidult and her inability to grow up, there is nothing you can really do about it. He's already told you "not to pressure her to get a job." This is his line in the sand. Something tells me that if you attempt to enact any house rules, responsibilities, or consequences, your DH will not be happy with you.

Understand, this most definitely IS a DH problem, and I'm guessing his unwillingness to prepare her for the real world, is not a new thing. If this is your first problem with SD, I'd be very surprised. Now you have to ask yourself some hard questions... how much am I willing to put up with? What is important to me?, etc.

First things first. Have an in-depth conversation with your DH just to see where he lands on all of this. Until you know what his thoughts are, you won't be able to strategize. Come up with a plan that you can both live with and then dig in. Do not make any rules that you don't plan on enforcing, b/c if you leave any doubt in SDs mind that you're not a united front, she will create a division in your home. Sadly, with blinder wearing bios, the SKs and their 'woe is me' crap, can sink a divided marriage. It will soon become apparent to you, where you stand is this situation. Hopefully, things will work out in your favor. However, don't be massively upset when you find that DH thinks it easier to give in to his kidult, than do the right thing as a parent. There is a reason this site exists, lol.

Best of luck to you.

What a pity for all involved, especially you. It's not your job to find her a job. If you don't want her there then make it uncomfortable for her to stay there so she'll find some sort of job and move in with a friend instead of rooming with you forever. One person I know solved the problem by getting a smaller house...with no guest room. A 60 day close meant everyone had to literally move on. Best thing they ever did. If you're not ready to do that, DH has to do the job he didn't years ago and that's stop enabling the SD to stay in limbo. It's not your job. As someone else said, military is an option, provides structure, training, goals--many life skills for those who lack them. It's a start. Good luck!