That's hardly new. What do you think happens to traffic when a semi flips over on a busy interstate, or electricity goes out, turning all traffic lights into 4 way stops and severely limiting throughput?
What happens when one company's engineering failure does that to most roads?
For reference, the US considers tactically blocking traffic to be something that smart terrorists or nation state adversaries would want to do to significantly harm the US economically.
What do these cars do if Google's entire self driving infrastructure falls over because some component gets misconfigured? It will happen eventually.
The only other option I can think of is to build some kind of high density low power solar powered IoT network that is independent of current infrastructure but then where is the spectrum for that?
https://www.telecomtrainer.com/lte-v2x-vs-nr-v2x-key-differe...