The edge cases they don't handle show up in their DMV accident reports. Google has been very upfront about their sideswipe by a bus. They mis-predicted what the bus driver would do.
The edge cases that they don't handle don't really show up in their accident reports, because they avoid testing them publicly until they have a reasonable chance at success at succeeding in controlled environments. The stuff you see showing up in accident reports are their Release Candidate bugs, not their Alpha bugs.
I think the main point is not that the system can handle all edge cases, but that it can handle more edge cases more reliably than humans can at the aggregate level. That is what really matters. A computer never gets drunk, tired, sleepy, sick, etc.
Furthermore, when autonomous vehicles become common, human drivers will also end up in fewer accidents because they won't have to worry about the unpredictable behaviors of other human drivers (such as suddenly changing lanes without signaling).
Edge cases are important, but at the end of the day, they're just that: edge cases. By definition, they will be very rare.
How they handle them is far more important than if they handle them. Human drivers aren't exactly great at handling edge cases either, but they certainly handle them better than the computers do at the moment and for the near future. Existing technology is by far better at the non-edge cases, but nowhere enough to make up for how bad they are at edge cases. They have better reaction times for people crossing the street, but throw some snow at it and it'll drive off a cliff.
I'm sure they've got some reasonably safe behavior for when it doesn't know what to do (do nothing!), but that doesn't exactly make for a great transportation device. Staying home is safer than that and just as effective at not getting you anywhere.
And while edge cases are by definition rare, how rare are they? I'd be willing to estimate that when I drove trucks for a living, I'd handle upwards of 100 scenarios per day that were not "by the books". Remember that 99.9% of uptime still means you are having downtime 1.5 minutes a day. If they are really bad at handling the edge cases at the 0.1% level of rarity, that's still enough of a chance to fuck up at least once a day.
>>Human drivers aren't exactly great at handling edge cases either, but they certainly handle them better than the computers do at the moment and for the near future.
