That would imply that cash is preferred, but, cash at a gas station - or any shop - is an attractor for robberies. At least with a skimmer the damage is purely financial, with robberies, especially in the US, there's a big risk of gun violence on top of that.
Can't rob someone that doesn't have cash, is all I'm saying.
You can absolutely rob a person that does not have cash though. Even ignoring the value of personal electronic devices credit cards themselves can be a target. You might be able to eventually unwind the financial impact but that doesn't deter robbery.
What you're describing sounds more like a mugging. He was talking about armed robbery of a convenience store. Is it possible to hold them up at gunpoint, forcibly take some of their card-processing equipment, and exfiltrate some money or credit card numbers that way? Probably, but that's not exactly the path of least resistance.
It's possible to steal a box of candy bars, or a case of beer, or the iPad cash register and on and on. Cash is not the only valuable a robber can target. Having large amounts of it on hand may make you a more appealing target but it is only one type of valuable.
Can't rob someone that doesn't have cash, is all I'm saying.