>Sheetz has 600+ locations and does $8b a year. All corporate owned and operated
600+ seems like a big number until you consider that there are 168,000 gas stations in the US. Large chains have a LONG way to go until they are more than a statistical blip, and this doesn't even take into account the fact that the federal government has, for over a century, cast a very jaundiced eye at any single entity using its market presence to drive competitors out of the retail gasoline business via undercutting on prices. Looking at the FTC ruling on the acquisition of Sunoco's fuel retail locations by 7-11, they monitor competition in fuel retailing VERY closely, to the point of mandating a certain degree of competition in specific markets.
Undercutting on gas prices is hardly the point. Most well-known chains charge more for gas -- and get away with it because their stores are cleaner, more convenient, have more pumps (so less waiting), and a far better C-store experience.
The store side is primarily where chains threaten independent operators because they can have a lower cost structure overall -- much more purchasing power on food/snacks/soda, more ability to offer fresh food (Wawa sandwiches, Racetrac frozen yogurt, etc), better stocking, and far more labor efficiency.
Your own number of 168k gas stations proves the point -- that number is from 2004, and is 40,000 less than a decade earlier. While there are many reasons why gas stations are closing, surely increased competition from brand-name mega-stores with 16, 24+ pumps each -- is one of those reasons.
Sheetz has 600+ locations and does $8b a year. All corporate owned and operated.