I've run into more failures than that at gas pumps, but it is mostly rare like you say. However in almost all cases, they're on the same network as the gas station POS, and I assume hard-wired. The card readers I see at EV spots seem to less durable, similar to the card readers you see on vending machines. I bet they mostly are using cellular to communicate.
That probably comes down to how the infrastructure is built out. A lot of companies are selling EV systems that can be installed in a pre-existing parking lot. A gas station requires installing large underground tanks, so it's not much extra effort to throw the data wires. In order to convince someone a business to install an EV charger, every little bit of effort counts.
