Yeah Google makes you share access to a credit card so you'll never add randoms

or your children

I don’t know about Google. But in Appleland you can have children in your family without letting them use the payment card associated with the family. You definitely can prevent them completely from buying anything (my situation), but IIRC you can also let them buy stuff once an adult has approved. It sounds like a reasonable system.

google has the same thing - purchase approvals so your kids can only request to purchase stuff, not actually purchase it

Then couldn't account sharers use the same trick?

I haven't seen a kids permission but I haven't tried. But maybe it's limited in other ways to make it useless