Here's one I noticed using Google Flights that appears to be an unexpected benefit. I use Google Flights as my quick-research method. And when i find something I then go to the airline site. But Google Flights also, after selecting the complete flights,,offers booking options, at that price, on the airline sites.
So my PHL-EDI, DUB -PHL trip, postponed 4 times and tentatively set for April, gave me options for booking on AA and BA. The BA did not work, BA will not sell that AA return flight without jacking the price enormously, with via that link or on ba.com. However, the "Book with AA" went straight to American with that trip ready to roll. However--if I go into American, I can't get that set of flights! There is one set I can get, but it comes again with a raised price over Google, and included an AAL flight out of Philadelphia that is not currently flying.
So how come via Google flights I can get an actual trip on American that i cannot get directly? Any ideas on this?