You are gravely and fundamentally underestimating the inattention and apathy of the average gas station employee, as well as the contempt a gas station owner has for his attendants. If I put on a suit, walked up to a pump with a master key, fucked around inside it and then reaffixed a seal I can guarantee you I'd get away with it 95% of the time, assuming the employee even knew I was there.I can't remember the last time I went to a gas station that is not 24 hours so, assuming it is not an inside job, I wonder how the scammers have time to install the skimmers without being seen.
You might be right but in Canada I am not aware of any mandatory pay in advance stations so perhaps attendants keep track of who is at what pump a bit more. A very quick google search leads me to believe that "gas and dash" fatalities (attendants being run down chasing a gas thief) are predominantly a Canadian phenomenon. I can't imagine why any attendant would put their life on the line for a tank of gas. Or why someone would run down an attendant and then go on the lam of 3 years for $112 worth of gas.