If humans can do it safely, a self driving car should (in the future when they really arrive) also be able to do it safely. But, what you describe does not mee

If humans can do it safely, a self driving car should (in the future when they really arrive) also be able to do it safely. But, what you describe does not meet the basic criteria for doing it safely. Regularly flowing at highway speeds in those conditions does not imply doing it safely, as much as you and those drivers might like it to. We read about pileups from time to time and the consequences of these are not trivial.