Comment by gorbypark

Looking into it further, it seems booking.com is only "sort of European". Booking.com (headquartered in Amsterdam) is actually owned by Booking Holdings (an American company), which seems to have originated as Priceline, which then bought booking.com and renamed/restructured itself into Booking Holdings and owns Priceline, kayak, booking.com, Agoda and a bunch of other airline/hotel aggregators.