I personally don’t like this concept–if a kid really needs a part-time menial job to take his studies seriously, I think there are bigger problems.
I can see value in having a job, but I’m more interested in my kid getting maximum value out of college, and if that means ECs that don’t pay, or volunteer work, or arts stuff, or just spending a lot of time on academics, that’s more important to me than earning their own spending money. Obviously, it’s different if it’s a necessity for the kid to work.