It's as if there were just put there one night by themselves many years ago. Clearly there must have been accompanying building and equipment but no trace seems to remain. It's a real "why" picture in that I always have to try and find a local who can explain it all. I find it difficult to leave until I get to the bottom of it, embarrassing the wife in the process.
Presumably the tanks are still there - unlikely the pumps would be there if the underground tanks were removed. Cleaning out and removing tanks with possibly leaded fuel remnants could be involved.
It's a form of archaeology - things are done for a reason, but we are often left with the residue and not the reason. Though Scottish Highland hotels are often the only habitation for miles. Arriving with an empty tank would be a problem.
I suppose there could be a parallel with American Gothic (Grant Wood).