Age verification is just like handing over your ID to the barkeep! It’s no different!
Except the barkeep keeps a copy of your driving licence in their vault that you can’t access, and then promises that they won’t offer copies of it to their friends, but you just have to trust the bartender that they won’t do it! They promise!
Plus, the barkeep promises the vault is really secure, even though there’s no way of checking how secure it is. They PROMISE that they won’t keep a copy of your driving licence forever.