Eli5: When your credit card doesn’t read at a credit card machine, why does covering it with a plastic bag suddenly make it work?

Question

Had this done multiple time at the register. Card not reading, so the cashier will cover the ribbon or the chip with a plastic bag and YATZEE, it goes through. Why?

In: 407

Answer 1

I know this isn’t an answer, but I feel it’s important and relevant.

Stop using mag swipes. Security is very poor. If the machine doesn’t accept chips, pay cash or go elsewhere if possible.