Nowadays, everyone needs a bank card, because it makes life much easier.
The sooner a child receives a card, the sooner he will learn to use it wisely.
Open an additional card in your name, set a comfortable limit for yourself (for example, no more than X rubles per day) and give it to your child.
Explain that this is his personal item, and the money on it is his money, real money.
Using a planned purchase as an example, show how to use the card online, at an ATM, and in a store.
If you pay your son or daughter for grades, help around the house, or some other work, or simply give them pocket money, allow them to choose how they will receive the funds: in cash or on a card (the agreed amount can also be divided in half - part in cash and part on a card).
Teach your child to top up their balance independently.
It is necessary to control your child’s spending, but it should be done discreetly: you give money to your child so that he learns to use it responsibly, and if he feels distrust on your part, the effect will be the opposite.
Either you teach your child responsibility, giving him reasonable freedom, or do not expect independence from him. There is no other way.