Differ all you want. No child will bankrupt a family at a trading card game store. These are physical goods paid in bulk with provisioning and there are laws for returning them.
Another point of contention is the randomness of packs. The way you play is: You save up to buy the entire set of boosters and already get almost all cards you need for competitive or fun play. The rest you need to trade for or buy individually. It is much more of a social interaction than gambling. The value you get from saving up and trading is easily 10x what you get from opening boosters.
That's why you will never see a bunch of kids queued up in front of a counter frothing from the mouth saying "just... one more!"
>No child will bankrupt a family at a trading card game store.
Let the child use a separate debit card? Bank cards are personal and work as an authentication factor.
You can't return an opened pack of Pokémon cards and more than you can get your money back for a used lottery ticket. It's absolutely gambling. Low stakes gambling maybe, but it's still gambling.
If you want to allow Pokémon cards and not casinos you have to accept that your rule isn't just "kids can't gamble".
Allowing trading is a big part of it. Most online games never allow trading the things bought with real money, they get tied to your account. I guess as a way to prevent CC fraud but it still contributes to the issue.