Neural networks are probabilistic. They output predictions and are rarely 100% confident. So when Tesla's visual neutral networks are assigning inferred labels to things like cars, bikes, pedestrians, road barriers, etc, there is always some chance, say, 0.1% that it's wrong.
If you have other sensors, like LIDAR, radar, and high resolution maps, then you can corroborate your predictions, so for example, if the visual system predicts a 99.9% chance you can make a safe right turn, checking the LIDAR and map will provide additional checks, even if your map is out of date. Consider:
1) camera system predicts you can make a right turn. You have no map, so you make it.
2) camera system predicts you can make a right turn, you have a map, the map says there's a wall there. You don't make the turn. If the map is wrong, you're still safe, you just missed your turn off.
3) camera system predicts you can make a right turn, you have a map, the map is out of date and says there's no wall there, but a new barrier has been erected and the map doesn't contain it. This is equivalent to situation #1
4) Same as #3 but you have SIDE RADAR, so you sense the barrier
5) Same as #3, but you have SIDE LIDAR, so you sense the barrier
The problem is, Tesla is not only going "all in" with their "we only need video cameras", but Elon Musk was asked directly at intersections if the lack of side radar was a problem, and he again fell back on "video is all you need", but if that's the case, why even have front radar?
Clearly, video is not enough, and if you have front radar, there's no reason to argue against side or rear radar, and by proxy, against LIDAR.
All of this comes down to the Tesla is shipped with a cheap and fixed sensor suite, they can't change it now, it's too late, and so they are trying to justify their previous design decisions with overconfident sales tactics and PR, and I think this is somewhat reckless and dangerous to the entire AV industry because the more Tesla's that crash and kill people, the more all AVs will be tarnished as dangerous by the public.
Musk is acting like Tesla is SpaceX and they can afford to blow up rockets or astronauts during iteration, but these are consumer products. People will trust these things to be safe, not to be "beta"