a right under check 21

Apparently people who want their checks returned have the right to at least a copy of the check
So if you are used to getting back used checks and they have stopped. Ask for the bank to send you copies - they should do so.

I remember when I used to get copies of all the signed Amex receipts with each statement - many years ago (I don't even have an american express card anymore). Nice, but I don't really miss them to be honest.