If one remote operator can supervise 10 mostly autonomous vehicles, you've gotten 90% of the economic value of full autonomy.
That's not to say you shouldn't dream big (it's a moonshot after all). But there are plenty of reasons to think it won't be viable even if they can solve the technical challenges, and that much still isn't even clear yet.
Customer support is also going to be far far fewer than one person per vehicle.
The enormous amounts of data? If it's not valuable they can just discard it! Having sensors attached to something doesn't obligate you to store it forever.
Everyone knows the software/configuration costs are immense here. But that's the lion's share of the difficulty, and there's no reason to act like minor hurdles are bigger than they are.
I'm curious what the legal requirements for this will be. But I imagine they'd want to hold on to data of driving scenarios for at least a month, in case they get accused of wrongdoing by other drivers. If they had no data to back up their case with all those sensors, it would look awfully suspicious and essentially one witness against nobody - so they'd have to hold onto the data for however long the legal teams deem is okay.
This may sound crazy, but it's already happening at the scale of testing with just a few dozen cars.
https://arstechnica.com/cars/2018/06/gm-settles-with-motorcy...
Though enough data to disprove a hit and run wouldn't actually take up very much space. Medium-resolution camera views and some acceleration data? Sure, pop a single SSD in there and it'll hold more than a month's logs.
Source: https://www.reddit.com/r/SelfDrivingCars/comments/e8bfse/way...
The real world is full of edge cases - cameras fogging up, proximity sensors confused by ice buildup, thick fog limiting visibility, sun low on the horizon blinding the cameras, badly marked construction sites, black ice, line markers under snow, potholes, slush, contradictory traffic signs, deep puddles, worn out ruts, suicidal wildlife, road debris, etc. etc.