No, it teaches them responsibility and teaches them the value of money...After age 19 NO MORE FREEBIES that's why these children get out in the real world and fail because their parents have crippled them...

Lol .. You said they are not making much, I don't think you should take whatever little they have.
But hey, your house your rules

every home is different and there are different ways to contribute other than money

I often use the example of an 'old fashioned' home where the FATHER worked and the mother stayed home,,,,although the mom isn't paying rent, she is making a large contribution taking care of the home and the children in the home, her payment is a healthy home instead of a paycheck she can spend,,,,but her 'work' is just as important of a contribution

likewise, older children can contribute through household responsibilities or paying rent or whatever contribution is needed in that household,,,

In Africa kids can leave with their parents until they are ready to get married, which means they must have found a job to support themselves, parents pay for their educations as well, but they do help out at home with chores