jonathan18:
I'll certainly not be encouraging my kids, when they get to that age, to take on such jobs. To me that's not teaching my kids the value of money, but rather teaching them it's ok to be screwed by The Man. Better that they put that time into something more valuable and rewarding in other ways.
I agree with your attitude - however you are fortunate to be in the position where you can support your children in that way. It's important to remember that not everyone can afford to do the same. At that age, some kids will consider it a fair trade to be screwed by "the man" in order to save enough for a ticket to the school ball or whatever.