Both sides claim they have consumers’ best interests in mind. Travel providers want stricter consumer standards for third-party sites. Online agencies argue that their business model - comparison shopping - is itself a consumer benefit and that airlines’ efforts to withhold flight or room data hurts travelers.

Travel providers are treading carefully because sites such as Booking.com or Expedia can amplify consumer awareness of available flights or rooms that providers haven’t sold directly. About 60% of reservations made online are directly through hotel and airline websites, according to travel market research firm Phocuswright - though that figure is falling.