ATMs very rarely inform users before they put their card in the slot whether it’s the kind of machine that uses a motor to suck your card into the machine. If yes, then avoiding the machine is a good idea.
The question is, how do you find out in advance whether the machine has a motor? Obviously if you test it on your actual valid bank card that you intend to use for the transaction, you may not get it back.
So my first thought was carry expired old bank cards which can be sacrificed. Stick the card in and if a motor pulls it in, hit the cancel button and try it on the next ATM until you find an ATM that does not suck the card in. This still has issues. The machine can vary well confiscate the card merely on the basis of being expired (thus invalid). Sure, it’s a sacrificial card but I don’t have 100+ such cards to spare. And also those dead cards will have my name on them and the ATM network could blackball my name.
So my next thought is to cut a rectangle from a plastic food container to use as a dummy card. It’s still dicey because criminals are deliberately sticking thin plastic sheets into card slots to cause the next real inserted card to get jammed (this is in fact one of many reasons why legit users should avoid the motorised card slots in the first place). But if you cause things to jam up, you could get treated like a criminal (camera → facial recognition… etc).
Maybe loyalty cards… grab a stack of loyalty cards from a grocery store and use those as dummy cards. Better ideas?
You know they spit the cards back out after you finish your transaction, right?
Not necessarily. The machine has a choice whether to give your card back or not. In Netherlands 4 out of ~17 ATM withdrawal attempts succeeded. A couple of the machines that rejected my perfectly valid and funded card did not have a motor, so there was no confiscation risk. A couple were Geldmaat machines, which do have the confiscation mechanism. They don’t disclose that on the machines but the website mentions it. I got lucky and Geldmaat returned my card. But the reason it gave for rejecting the card is the same reason some machines will confiscate cards. I was lucky I was able to get my card back and use an ATM by a different operator, which accepted my card. Had the ATM confiscated the card, I would not have had the chance to try other ATMs.