I think this accounts for the increased use. I would go out of my way to avoid taking a Taxi because they're so inconvenient and opaque.

I still don't plan to start using Uber extensively because I'm used to walking at this point, but the combination of transparent upfront pricing, accountability, ease of use, speed of pickup, and seemingly typically lower pricing is a compelling case versus zip car. Definitely an actual competitor with walking and public transit, whereas I see Taxis as only really a competitor with driving.