I don’t know how it compares to Windows and Android, but in South East Asia I get “mobile prices” on my iPhone and they’re actually lower than on the desktop.

South America/Europe here. Booking.com does the same, cheaper prices on mobile than via desktop/laptop.

That's what they advertise, but multiple times when checking the price is absolutely the same on desktop (from a different account). They've already been caught in false advertising so i don't see why they continue to do it

Prices are so flexible I usually find a hotel and then Google it to find a better price, even if I end up on the same site. The worst thing is when they advertise a price without taxes, which unfortunately is not illegal in most of the world. I think in Europe you’re required to show the final price.

This is very common with vehicle and house insurance. Getting a quote from iPhone results in a higher quote than using Firefox