It tends to be a token amount and really more a symbolic contribution.
Plus it begins in some small way to teach them vital skills.
how many 20 somethings (or 30 somethings. ) are unleashed on the world who are shocked to find you need to pay rent, gas, electric, water rates, phone bill, internet bill,council tax, perhaps tv, and that the food cupboards and non food consumables eg washing powder, deodorant, loo roll... aren't magically provided by the Tesco Fairy?
not to mention insurance- car, home, maybe life...
you get them actually complaining that they've got no money cos everything goes on bills. hurumph.
To them, I wish to say Yes. Welcome to the Adult World
The world where life is primarily paying your bills and most of us have very little left over.
If they've never had to fork out a thing, this is a massive shock to them. If they know that they have to pay X, Y, Z first and then what's left over is theirs, then they're beginning to get the hang of it. 