More than safety, the allure of self driving is that computers could smooth out traffic and speed up starting etc. And that is if the cars themselves can talk to each other.

If all cars could talk to each other they would be able to accelerate from a red light simultaneously (like a train), greatly decreasing transit times, as well as increasing throughput.

Same with merging and lane changes, they can be done precisely and smoothly if cars could cooperate. (Zipper merges would be magic)

Also, because the cars could theoretically know where everyone else is going, the can distribute traffic across multiple routes to optimize overall times.

And even in an instance where a car, say loses control, all the nearby cars could more easily avoid it without hitting a second vehicle. (and can not just let the car behind it know if it’s braking etc, but all the cars behind it, or even pass on relevant information to cars way behind, like if you get into bumper to bumper traffic, you can redirect vehicles that haven’t yet reached the traffic to reroute before you get there)

Even parked cars could all start to self adjust to increase parking, or to move out of the way of impact etc