One other thing, is that minimum-wage jobs are often (not always) filled with entry-level workers. These are people who have never had a regular job. They don't know, or may have unrealistic ideas about the importance of being on time, showing up when scheduled, not taking random time off with short notice, etc. So policies are strict because many workers need to be "trained" about what to expect.
This effect extends thru the entire economy.
From observation its not that people who are poor have no ambition, they just have ambition in areas not involving getting lots of money from work or "reward" from management recognition. They want a happy family life, sex, be cool, get drunk often, ambition in all manner of things, just not into working 10x harder for 2x more money. I probably work 100x harder mentally than when I was a high school kid working at a supermarket and I barely make 10x as much money. For me working 100x harder is not a big deal because supermarket work is not exactly rocket surgery, but I can see a lower ability normie not seeing 100x harder work as achievable without excessive stress for them at their performance level, or perhaps being impossible for them. The "sit at home" under a UBI scenario seems incredibly unlikely. You might not agree with or appreciate the effort of "being cool" or posting high score posts on facebook or obtaining sex, but they will certainly sweat a lot of effort into achieving it. Playing video games is not very profitable but it is somewhat ambitious and takes a lot of effort.
To some extent a marketplace that doesn't meet the participants needs is a failure of that marketplace, which describes a lot of our labor system for a very large fraction of the population. Its not really their fault the system is irrelevant to their interests.
Sure, I worked a lot of retail/physical labor/etc. type jobs in my younger years. I was out of the house at an early age, and took these jobs very seriously since they paid my bills. My co-workers for many reasons did not, at least a very significant minority of them.
I don't think it's really "out there" to say that the typical minimum wage worker is not as high quality as the guy 4 years in making $20/hr. That is reflected in their pay, after all. The folks I worked with were either generally reliable and usually job hopped quite a bit every 6-12mo for raises, or they were just workers who barely had enough value to not get fired. The latter were more common, in my experience. Despite what you hear on HN and elsewhere - there are a significant number of people who have zero interest in working, and only do so to pay bills. If they could sit at home all day doing nothing, they absolutely would. Working with them is not fun, and until I found the whole computer/on-line community thing (in the early 90's) I felt extremely alone spending most of my day with those types that had zero ambition to improve their lot in life.
And I think it's more of a "masses" problem - not necessarily class based. Maybe investment based. You likely don't really care much about your $7/hr job, at least a significant portion of people do not. That same is not as true for the $100/hr job. It's simply a filter.
You see the same issues in other "body shop" style white collar offices too. Even relatively highly paid folks like insurance call center workers have to be treated like children, or you'd have half the office call out on a friday before a long weekend. Been there, done that as well. I imagine Infosys and similar companies have policies that look very similar to someone like Walmart.
I'm obviously having trouble describing my thoughts here - but in the end I'd say it's something like professional careerists vs. a just a job. The latter there is very little skin in the game for the average employee comparatively - and those that have that motivation generally don't stay in that socioeconomic class very long. You see the same effects in any space open to various segments of the public. The higher your admission fee the less you have to pay for people destroying things. More skin in the game.
Edit: I think it's important to state these are generalities. The actual working poor tend to be by far the hardest working most reliable folks out there. If they had issues making it to work - it was usually something huge in their lives. The thing is though? These folks typically got promoted or much better paying jobs elsewhere, so it's again a self-selection thing. Sort of like stack ranking your employees and only the lower 50% get to stay in your company.