I guess you've never bought a bottles water at a gas station!
No guessing about it, you're right, I never have purchased a bottle of water at a gas station, or a bottle of pop/cola at one either. Only thing I've ever bought at a gas station is gas and oil, never anything else. That is in over 50 years of driving.
However I have purchased gas which is controlled by the speculators.
Oh wait, cigs in my younger more foolish days.