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.
I don't know if your experience is from British people but it looks like they just didn't have the mean to effectively compare fuel prices.
Once they do, there is a significant part of the British drivers that will most likely be using it.
We have a system here in Western Australia and people use it a lot: fuelwatch.wa.gov.au
I think it's exactly that, the UK has never had this so people there either choose by brand or just convenience. But since moving to WA I've found that it's really easy to have a quick look when I notice I need to fill up, then I can head to the cheapest station nearby, and the difference can be in the range of 10-15%, occasionally 20%.
In a country where fuel is as expensive as it is in the UK, people are going to use that.
Disagree - drivers maintain a mental map of local stations and know roughly how expensive they are, and make a decision based on that. Obviously this API will help inform us better!
Maybe it's me that's weird. No, surely that can't be right... :)