You may soon have a real reason to use a "metasearch" site such as Kayak or Travago to find your European hotel room, rather than an actual booking site such as Booking.com or Expedia. Up to now, almost all prices have been the same; that may be about to change.
Booking.com, a part of the Priceline empire, and the leading hotel booking site for Europe, has contracts with hotels that guarantee that it will be offered the best rates anyone else has been offered—that's referred to as a "most-favored nation" clause. Regulators in France, Italy and Sweden (and closely watched by others) have argued that these clauses stifle competition and favor the larger agencies. Yes, there are special rates here and there, but mostly not.
Now Booking.com has agreed with the regulators to give up the price parity deals; this means hotels and chains could negotiate all sorts of deals with different agencies—and the only way you and I could keep up with them would be to either check dozens of seller websites (booking.com, Expedia, hotels.com, etc.), or choose one aggregator such as Kayak or Trivago that would show all the different prices.
Industry news site Skift has more thoughts HERE