from people who work in those companies:

those cars could be in every city and they’d run great (except snow. snow is tough, rain not so much)

but why aren’t driverless cars there?

It’s been decided you want a perfect track record, as close to flawless - to appease regulation bodies.

regulation is what kills and regulation is the biggest fear. The cars and tech are always getting better, the ‘slowness’ is deliberate, the bet is on the future.