My bank authenticates with me before honouring a check - is this not common?

I'm from the US and I've never heard of a bank verifying permission before releasing funds, they simply release the funds. As far as I know, US banks no longer check the signature (if they ever did) and no longer validate the date on the check (at least at my bank you can no longer post-date a check).

We recently lost a book of checks and the bank totally wigged out. They demanded that we close the account immediately and it took a decent amount of back and forth to talk them into waiting a week (we wanted existing checks to clear). To my mind, this implied that they did no validation on checks.

I haven't actually used a check in a looong time so I don't know exactly what you mean.

I do know that I keep the numbers off a check from my checkbook I received when originally opening my bank account like 10 years ago in Lastpass. When sites that don't accept credit need payment information (my student loans mainly) I just copy/paste the numbers into their payment form and the money gets taken out of my account. No verification whatsoever, Nelnet is able to just withdraw the money from my account using those numbers.

I assume anybody with a debit processing backend or service can do the same if they have the routing/account #. It's kind of a wonder peoples money doesn't just disappear all the time really.