A good example would be the area around Lancaster Pennsylvania. With Amish horse drawn buggies, people pass them on double yellow lines all the time. I don’t know if that is legal, but where I live in New Mexico we have a similar, if less common occurrence with farm equipment on the road—everyone passes them, though technically it’s a traffic violation. In some of these instances the speed difference is significant enough (10mph in a 50mph zone) that it could easily be more significant than 10 minutes on an hour drive.
It makes me wonder about traffic laws, and whether there will be a push to make these behaviors more explicit laws because there is potentially huge issue if Waymo or other companies program breaking laws into their driving code. Add to that that traffic laws in the USA are primarily state laws, but municipalities frequently have additional laws. The laws are all mostly the same, so I suspect autonomous vehicles will be programmed to the most restrictive of the laws.