I would have to beg my dad to use his credit card to make an online purchase, even if I had the cash equivalent in my hand to give to him right then!
If I new kids would be using any device I would make sure it had no payment information accessible. Which may mean the inconvenience of adding and removing payment information before and after making purchases. I can't imagine letting a child have access to a device which can spend your money, it's essentially like letting them hold your wallet, and we probably wouldn't trust them to do that if they were in an arcade, or theatre, or shopping mall, etc.