It's true that a careful, experienced driver will typically recognise a rapidly emerging hazard as much as several tenths of a second faster than a novice, giving them significantly more time and space to react. However, a careful, experienced driver will also anticipate places where there are likely to be hazards and adjust their driving style to compensate.
Does a self-driving car know that there's a park just round the corner and it's half an hour after the local kids came out of school, thus increasing the risk of a child chasing a ball into the road?
Does a self-driving car understand that the group of people standing quite near the road up ahead are outside a bar at 11:30pm and thus quite likely to be drunk and suddenly stagger into the road?
Does a self-driving car know about the pothole in the cycle lane that you had to avoid while riding into town yesterday, and anticipate that anyone riding in that cycle lane today may move out into the main traffic lane without warning to go around it?
Does a self-driving car know that the news last night reported on a local black spot for "accidents" caused by people wanting to make fake insurance claims, and decide to take another route that is a little slower but avoids that black spot?
Better sensors, fast data processing, and the ability to monitor all sensors all the time are big advantages, for sure, but these things mostly support reactive behaviour. I've seen nothing so far to suggest that the better reactions currently outweigh proactively avoiding or mitigating these kinds of hazards in the first place. Obviously that might change in any number of ways in the future, but we seem to be a long, long way from that point yet.
On your second point, the important thing here is that you don't need to disperse much of this information to humans. Humans automatically recognise situations based on all of their experience, not just their driving experience. Of course sometimes external information sources like the news might be helpful, but much of it is just down to understanding context. See fresh horse crap on a country road? Someone's probably riding horses nearby. Horses scare easily. So, slow down and try to avoid anything noisy that could startle the animals. How many of today's self-driving algorithms take into account this kind of implied knowledge?
