The overthinking involved in this stuff is bizarre.
I might have done it when I was younger and didn't have any of that, but that kind of work didn't really exist beyond pizza delivery. I worked at a video rental store, instead.
Crappy jobs are a motivation to improve.
One bad head injury could do all that and more. What are you going to improve then?
My point here is that given other choices, people don't freely choose precarious low wage work. It's safe to assume that people doing those jobs have pressures and constraints on them that limit their choices. This is why they're "willing" to do shitty work. You could be coerced into it too, given the right conditions. Understand the incentives, don't just justify it away as "freely chosen" because it isn't. To some extent that's true of all of us, but not to the same extent and the difference is meaningful.
I think if you could find some curiosity about why they make those choices it might take you to interesting places, but I can't make you.
Everything is a trade off. You could choose to be a software engineer, but it requires a big investment of your time and making critical life choices at the right moments. Much more difficult than simply running gigs.
People are free to choose and they take on the consequences of their choices, good or bad.
Edit, because people share a characteristic with heavy metals: the point is that a “choice” made under economic duress is not made freely. Slavery is an extreme example used to make the point more obvious. The threat of violence used to compel people to work the fields is obviously worse than, but not necessarily qualitatively different from, the threat of abject poverty if one refuses to take low-paying insecure jobs.
I'm not even sure how you can explain what free market labor is without referring to slavery, or explain what slavery is without referring to free market labor i.e. I don't think it's possible not to compare them and rationally talk about either of them.
In all seriousness, refusing to compare two things because you think they're "just too different" is simply acting irrationally. Look at the objectives, pressures, and outputs of each system and you may see more similarities than you'd like.