Oh, I'm pretty sure that self driving software isn't being programmed to systematically disregard speed limits to match traffic, not even by a company with Uber's attitude towards regulations, but it is an example of conditions where rigid adherence to speed limits might increase rather than reduce risk.

With enough self-driving cars on the road (which of course there aren't now), rigid adherence to speed limits might change the safest-and-easiest driving speed for everyone and lead to everyone driving at the limit rather than everyone everyone driving 5mph (or 10mph or whatever) above the limit.

So the safest reasonable thing for self-driving cars to do could depend on how many of them there are around.

(Of course there are other considerations of that sort. E.g., if all cars on the roads were self-driving then they could coordinate with one another in interesting ways and maybe go substantially faster than human-driven cars for a given level of safety. Maybe not, though, because of risks to pedestrians.)

Hmm, turns out Google cars are programmed to go over speed limits in certain situations. Quote from a Reuters article:

Google’s driverless car is programmed to stay within the speed limit, mostly. Research shows that sticking to the speed limit when other cars are going much faster actually can be dangerous, Dolgov says, so its autonomous car can go up to 10 mph (16 kph) above the speed limit when traffic conditions warrant.

https://uk.reuters.com/article/us-google-driverless/look-no-...

I wonder how they decide over what warrants speeding.