nah. there’s people out there whose favourite thing is to do the niche “yucky” or tedious things, but they can’t, because they had to get a job in marketing, or work in retail because they needed ANY job just so they could survive.

This is one of those ideas that only makes sense at the surface level and fails at the slightest bit of scrutiny. Yes, it is technically correct that any job out there will have some nonzero number of people who would do it just because they want to. But that's no way to run a civilization.

That system only works if there just by random coincidence happens to be a perfect match between the jobs people want to do and the jobs that need doing. Are there are a few weirdos that would wade waist-deep in literal shit to clean out sewers for free, just because they enjoy it? It's a big world and people are weird, so there probably are a few people out there like that. Are there enough of those rare weirdos to keep all our sewers operating? Highly unlikely.

I know your system would fail because we have clear evidence from our own economy that there is a major mismatch between the jobs people want and the jobs that need doing. Look at every job out there that attracts people who want to do the job for its own sake. Look at university teaching, for instance. Universities can get away with having classes taught by poorly paid adjuncts because lots of people would like to teach university courses. There are far more potential university lecturers out there than the number of lecturers universities can actually support. Universities can pay their adjuncts a pittance, and they still have people sign up to teach classes. The low adjunct pay problem would disappear tomorrow if people simply stopped taking adjunct teaching jobs.

Look around to nearly any field that people go into primarily out of passion. They nearly all pay a pittance. "Let people choose whatever job they want" simply isn't a viable way of running an economy. Everyone wants to teach kids or care for puppies. No one wants to clean out sewers.

You always have to have some way of getting people to work jobs that they wouldn't choose voluntarily. There are simply things that need to be done for society to function that not many people want to do. In a capitalist system, this is done by offering higher wages for positions few people want. In socialist systems, this looks like offering more perks like better housing to unwanted jobs (pay by another name.) But you're trying to hand waive away an unavoidable problem by dismissing it as, "no worries, people will just do what they want and things will work out!"

Yes, I'm sure plenty of people actually wanted to become plumbers, farmers or construction workers, but had to settle for a job in marketing or such because that was all they could find.

You mean people who got the jobs they could get and would prefer not working those jobs if they could get away with it. Trust me, a lot of people working physically demanding jobs don't do it because of their enjoyment of wrecking their own bodies.