I'm not arguing the OP's point but...

A fair wage represents an exchange of equal value. This does not speak to the viability of repeating that exchange as profession; only that reasonable compensation has been given for a reasonable amount of work.

No. I’ve probably had 20+ jobs in my lifetime and only expected to make enough to live with maybe half of them . The idea that working fast food, which I’ve done and anyone with a pulse could do, should pay enough to pay all of an adults living expenses is preposterous and makes no economic sense at all.

Yes. That's not the whole point of all jobs.

OP mentioned that the coffe shop show was staffed with 17-20 years olds. They don’t need to earn 20 bucks per hour, they don’t need to be able to afford mortgage, or even rent apartment by themselves (they can have roommates). No one would work such job their whole life anyway. It’s temporary almost by definition