There's a talk from Travis Kalanick recently on a podcast about this. It talks about the advantages of a startup vs an incumbent. My read is if a startup competes on price, the incumbent has no choice but to first let them gain a bunch of market share. It's too expensive for the incumbents to compete on price because a no-name startup is doing it. So they'd have to let you get relevant enough for it to make sense to compete on that axis.

I view it as a wedge to gain market share and later compete on something else.