This, exactly. And more critically, because of the non-mediated nature of the interaction (that is, Uber is an absent middleman for the actual customer experience), drivers themselves can push passengers to other services. For example, a new arrival to the space could offer drivers a promotion for each new passenger-customer they recruit with a code. Driver is driving for Uber, hands passenger a card with the new service info and a $20-off code so they try it. No stickiness at all.