There aren't any RIM-like companies in the car industry right now. And cars aren't really very useful as computers. Or at least not more useful than phones and tablets and laptops.
They simply thought it was too hard and went back to what was already working.
Taxis and buses are pretty old tech at this point. (Not just from an Uber/Lyft perspective either; taxis and coaches predate cars themselves, because the ideas/"tech" worked just fine with actual horse power.)
As for self-driving cars, so much of the efforts today remind me of that old Ford quote to the tune of "If I asked people what they wanted, they would have asked for a better horse". It doesn't feel like an innovative step change in transportation, it feels like a slightly better car (when it works). It doesn't fix any of the current big problems of cars and over-relying on cars as our primary transportation form factor.
