It is the same in the US and this is the main reason for the disappearance of small gas stations. Some of the other reasons mentioned have an impact but mainly the small guys cannot compete with the big boys. The big stores and chains can negotiate more favorable contracts with the suppliers and get a better price. It isn’t that each outlet negotiates for the price, the corporate office for ALL the sites sets up regional contracts.
And then they offer the in-store discount cards that rack up points so you occasionally get another small discount. So this attracts people who think they are saving money by shaving a few cents off a gallon.
Over a year you might get a free gallon or so but some people make their buying decisions based solely on the price per gallon. They will drive extra miles to save a few cents! Boggles the mind.
I assume that the station had a large capital investment in the lifts and other things needed for the service bay. If you had a good mechanic with a following, you could do okay, but in recent years there is a lot of competition from specialized oil change franchises and dealers pushing their service departments. Convenience stores get more continuous business, and the extra cost might be worth not having to wait in grocery store lines or making an extra trip. You’re at the gas station already, after all.
Abandoning tanks by filling them with sand was typical in our area, back in the day. Not sure when you’d have to take out a tank that wasn’t leaking. My wild guess is that as long as it’s there, it would need an operating permit.
Pay at the pump can’t be doing them any good. If you don’t even have to go in the store to pay for your gas those high margin inside sales don’t happen. They could stop taking the cards at the pump I suppose, but then a lot of people won’t buy gas there.