That is clearly not true. See, for example: http://www.iata.org/pressroom/pr/Pages/2016-12-08-01.aspx
If I'm flying from NYC to DAL, I'm flying the cheapest carrier (with a slight nod to Frequent Flyer programs).
It's true that many people bargain hunt, but the people that don't (primarily business people who need to fly on short notice and on fixed schedules) subsidize lower fares for those who do.
At the moment, it is the investors who are subsidizing lower fares at Uber and Lyft, to the tune of billions of dollars per year. You're right about the autonomous cars. At this rate, Uber will run out of money before autonomous cars can save it. And even if they do, Uber will be a low margin business.