ya'll realize the gas all pretty much comes from the same place right? my last job included ordering fuel for an entire university (7000 gallons of 87 reg, and 2000 gal of on-road diesel at a time).
i had 5 choices of companies for fuel. i had to get bids from 3, and choose the winning bid and facilitate delivery. at least one company was in indiana (i'm in arkansas). if they won the bid, they just ordered from another company closer to us and paid them to deliver the fuel. doesn't really make sense at first (why not just order direct from that company right?) well, gas companies buy from each other for better prices.
"public" gas stations are similar. if its cheaper to order/deliver to a certain location from a rival company, they'll do it. the difference is in the tanks under the station. type/age/maintenance of tanks plays a bigger factor than the gas itself.
and yes, i've seen the "out of order" labels. just like the pumps that pump more with each click. tricking the people that don't pay attention, out of even more money. kinda like "buy in the next 10 minutes" TV commercials. I call them all "stupid tax"