I didn't have a debit card until I went to university :P I _think_ having a card at 11 is rare, but not sure. Also maybe gen z/etc are getting cards earlier? Also not sure if parents who do get their kids cards at a young age aren't also checking their statements. Not sure if there's any data on this.

In the UK, "GoHenry" is an app that is targeted at parents as a way to give your kids pocket money, and comes with a debit card option. Their target age range is 6-18.

Revolut also offers accounts from age 6.

Parents would get notifications, but I suspect most parents won't be technically inclined enough to have an issue with a well argued child pointing out they need that VPN to access a game server or region locked content that their parents don't object to.

That said, I'd suspect most kids looking to circumvent these blocks will just install a free VPN.

Wasn't particularly rare when I was in middle school and would've been odd not to in secondary. Bet it's only more common now.

There's also non-bank pre-pay cash cards such as Henry I think one's called, so parent loads it up with pocket money or whatever and I think gets more control/oversight than actual banks probably offer even on dedicated children's accounts.