There's a big difference. Sites like Expedia you actually go through their checkout process and pay them, then they integrate with the airline system to make a

There's a big difference. Sites like Expedia you actually go through their checkout process and pay them, then they integrate with the airline system to make a reservation. If you want to make a change you have to go through Expedia instead of the airline. You have a terms of service agreement with Expedia, etc. It's a full intermediary. Google never takes your money for the flight or manages a reservation.