All of my experience is flying in lower Southeast Alaska where we use air taxis/float and wheel, to get out to the outer islands and areas where there are no roads or water access to. 
People fly in and out for doctor and dentist appointments, shopping, and to get to Ketchikan to catch a ferry or jet to further destinations. 
I think the difference in tipping, is the air taxi's who fly summer visitors on pre-arranged tours. Most of the passenger are off the cruise ships and take a Misty Fjord's flight tour or a Bear tour. 
There are also the folks who come up and are flown out to remote forest service cabins, they charter the plane and tip the pilot for returning to pick them up. 
The air taxi /float pilots work for companies with staff support for freight and  mail delivery.
Our "bush" is flying over water and 17 plus million acres of Tongass National Forest and Misty Fjord Wilderness and National Monument. The temperate rain forest weather is a huge challenge daily,12 months a year.