[ajross]

Maybe. But the fact that Uber and Lyft are actively competing (both with taxis and each other) using that model would be a pretty strong argument to the contrary.

At the end of the day, antitrust legislation exists to protect consumers and markets, not established businesses. Prices under cost, in isolation, pretty much can't be antitrust violations by definition. They have to be used to effect a harm to the market in other ways.