From what device? I just did the same search from within the UK and it localised via IP address and served me the booksellers as the top search result.

From anywhere outside the UK I’d be shocked to see the booksellers listed at all.

From my laptop, in the UK.

Did you use Bing search? Do you have an ad-blocker?

Yes. No. iOS device, both Safari and Firefox focus, location services disabled.

[ For those unfamiliar - Waterstones is a major British bookstore chain, with >300 stores, >3,000 employees, etc. https://www.waterstones.com/ ]

Google pays $billions to Apple to be "unfairly" favored for search, Amazon doubtless pays Microsoft extremely well for similar treatment.

It'd be nice if Waterstones' legal folks could do something...but my bet would be "nope".

It's an ad, not an algorithmic change, so Amazon indeed pays.

*) I'd say clearly marked but of course the [Ad] is kept in toned down colors to make it not obvious

Waterstones every result on the page on my phone.