I know someone who avoids their local petrol station that is 10p/litre cheaper than most others nearby (within a mile or so) as they think the cheaper fuel must be lower quality. There are weird status things going on with purchases like this.
Only the other day my father refused to buy some branded paracetamol because it was ~5 times more expensive than the local pharmacy brand that was out of stock. (£2.25 vs £0.49 for 16 500mg tablets.) I'd usually agree with him but he was out of paracetamol and has been advised by his doctor to take 2x500mg a day and there was no viable nearby alternative.
A digression but for that generation (those born in 1940s/50s) that grew up with rationing I think it is hardwired into their brain to try and minimise the cost of so many things, but with lots of random exceptions. Later on that day he ordered an extra drink but decided he was too full once it had arrived so he left it. So he was worried about spending an extra £1.76 on paracetamol but not about spending £7 on a pint he didn't drink.
Many people decide what petrol station to use based on simply how close it is, what kind of shop is attached to it (and the bits of British snobbery around that), whether it also sells whatever else they want (bread, milk, beer, etc), or even whether it is easy to drive in and out of.
Sadly many people feel that because they are sick, they need to spend as much money as possible because that would give them best shot at getting healthly.
I once asked a guy "why don't you buy that cheap medicine. Its the same and will save you money" but they were like "naa. Its cheap. What would be inside it. I need to pay top money for best medicine"