The obvious solution is to find some of the cards that have been used at these places and deactivate the card so it can’t be used.
The welfare card holder will call to ask why their card is not working and you tell them to come on down, we want to talk to you.
Give them a warning. Tell them if it happens again their card will be cancelled and their benefits will come by mail but no more card.
Political Correctness prevents us from fixing the problem.
First step is to identify the problem: EBT is a poll-tax against people who work for a living ( I know there are exceptions).