Well that's a double edged sword. There's so much fluctuation in part because it's such a ubiquitous commodity, availability is high and margins are low.
If branding mattered more (like with groceries) then prices would be more stable (but higher).
But as it is, nobody cares that much what brand of gas they get, it's just gas. A name brand can't demand a higher price just because it's a name brand, nobody cares.
Society would collectively say get your shit together on pricing! And we'd never buy bread again.
I mean, prices at the pump aren't fluctuating that much, but I do get your meaning. That said, in general people don't really have much of a choice when it comes to food, we have to eat. I mean, do you remember how eggs surged in price during the pandemic years? People still bought them, it just sucked. Oh we complained about it alright! But we as a society didn't do anything