I've had this conversation with my adult child who struggled with job hunting due to disability.
I focused more on 'you will need to contribute to the house at an adult level' and 'as an adult, you're responsible for continung your development, and I am here to help with that.' We discussed and agreed what that would look like for him, and how his father and I could help him keep himself on track. While it would have been a struggle financially, taking a significant part of the home workload is also a means of contributing.
For job specifically, I gave a time limit for looking for career job hunting before it would need to be any job to continue to develop skills. I assisted with building CV and interview skills, recommended job fairs both to find work and they are often also supported by and have places that run programmes similar to what the Job Centre would do without being the Job Centre - training training programmes with guaranteed interviews, regularly support for working, and so on. There are loads of options out there, though they vary a lot by region, which is why local job fairs can help. Also, the local council may run an employment newsletter - where I am, there is a weekly one that discusses programmes like the above, employers that will be at the job centre, and more which we used and looked at together. Looking at temp agencies can also be helpful, particularly for those still working out their strengths and how they work best.
My son got an any job for 9-10 months working part-time while working on other stuff, and all that together led to him getting into a sponsored cadetship programme. He worked a few more months part time before the cadetship started, and it made things a lot easier to have his savings going into that programme even with the bursary.
At 20 she would have been shown how to do this at school, college, by a respectable adult in her life surely.
Like many things in education, some do this well, others fling websites or things like Unifrog at the kids and expect them to manage it themselves. I've seen CVs coming out of the schools and colleges that hit everything employers hate - big bold coloured borders 'to show personality', generic and often inaccurate skills ('great communication skills' means very little and I've seen kids with communication related disabilities put that on their CVs because 'the teacher told them too') that have nothing directly to do with the position. I think teenagers and young adults need a lot better support than many of them get.