How were soldiers, sailors, etc, paid during WW2?

It’s a little more efficient than that. They have you sitting in a room and a representative from a local bank hands out 1 page forms where you can sign up for a checking account if you don’t have one. That bank happened to have ATM branches right on post, of course. (and the checking account did not have any monthly fees, so it was more or less on the up and up.)