What's the advantage of doing paid work in high school

I think it is all good, especially if you aspire to “well-roundedness” for your kid.
It’s great for them to be in a professional, not school situation. You, the parent, have no involvement in this. It is their responsibility to be on time, to learn their duties, to communicate with the public and management about various things. D23 has worked in a deli and now a busy restaurant - she demonstrates how responsible she is every week.
D23 has worked with all sorts of people, some good, some not so great. I get the feeling that it has made her very grateful - she has worked with some kids who don’t have her advantages. It’s widened her friend circle. She’s been pretty good about communicating with her manager about time off for studying or events, but sometimes her schedule is stressful/a alot. That’s probably the only negative.
Also-she gets paid! And it’s very sweet when your kid wants to take you out and treat you with their own money.