LOL - My father was a mechanic and owned his own "garage" since was 17 years old. I'd love to see one of these rude SOB's park their vehicles at one of his two pumps for an extended stay. It would get moved pretty darn quick if you get my drift LOL. But then again, no one would loiter at his garage - no need to; no food, no lottery tickets, no smokes. Just gas and repairs. And a cranky owner if you p*ssed him off (or blocked him pumps) :)
I mostly get upset at the managers of these gas stations b/c they will allow this rude behavior even if it's brought to their attention. They'd rather be accommodating to the rude ones at the expense of the waiting ones... but they make enough that they just don't care about customer relations b/c there is another car waiting to fill up as soon as you leave.
You usually don't run into this at smaller places, just at fuel stops along interstates. The smaller convenience stores will still move those people along in order to keep the long term customers happy.