This is a great innovation and I'm sure in time it'll become a useful source of information. There are some edge cases of course.

If you live on the Irish border, you'll have a choice between getting your petrol on the UK side, or the Irish side. For about 20 years, petrol was cheaper on the Irish side, causing a bunch of petrol stations to spring up just over the border, attracting drivers from the other side with cheap prices and good exchange rates.

In the last 10 years or so, the position has reversed. Petrol is now roughly cheaper on the UK side of the border, or at least not worth making a special trip for.

There's even a petrol station in Belleek mentioned here[1] that straddles the border and apparently has or had pumps on both sides.

[1]: https://www.impartialreporter.com/news/25653110.border-filli...