Comment by derefr

> There is a difference between "putting up a sign that says 55 mph and walking away", "putting up a sign that says 55 mph and occasionally enforcing it with expensive humans when they get around to it", and "putting up a sign that says 55 mph and rigidly enforcing it to the exact mph through a robot". Nominally, the law is "don't go faster than 55 mph". Realistically, those are three completely different policies in every way that matters.

...and there's also a large difference between any of those three shifts, and the secular shift (i.e. through no change in regulatory implementation whatsoever!) that occurs when the majority of traffic begins to consist of autonomous vehicles that completely ignore the de facto flow-of-traffic speeds, because they've been programmed to rigorously follow the all laws, including posted de jure speed limits (because the car companies want to CYA.)

Which is to say: even if regulators do literally nothing, they might eventually have to change the letter of the law to better match the de facto spirit of the law, lest we are overcome by a world of robotic "work to rule" inefficiencies.

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Also, a complete tangent: there's also an even-bigger difference between any of those shifts, and the shift that occurs when traffic calming measures are imposed on the road (narrowing, adding medians, adding curves, etc.) Speed limits are an extremely weird category of regulation, as they try to "prompt" humans to control their behavior in a way that runs directly counter to the way the road has been designed (by the very state imposing the regulations!) to "read" as being high- or low-speed. Ideally, "speed limits" wouldn't be a regulatory cudgel at all; they'd just be an internal analytical calculation on the way to to figuring out how to design the road, so that it feels unsafe to go beyond the "speed limit" speed.