Because people passing you is very slightly more dangerous than people following you. It’s not a big deal most of the time, but when everyone passes you across thousands of hours it adds up to a significant risk.

Why would anyone want to pass you when you’re moving at the speed limit? You are at the speed limit and everyone passing you would be beyond the speed limit.

I honestly can't tell if you're trolling or not. They would want to pass you because human drivers aren't rigidly law abiding machines. Is there a large portion of people that go exactly the speed limit, or even lower? Sure. Is there also a large portion of people that speed virtually every moment they're behind the wheel? Yes, absolutely. And I wouldn't be surprised if that were the larger population in most areas. No one who actually drives with any regularity would ever be surprised that people are speeding to pass them.

Nobody is saying autopilot "needs" to speed to be safe at all times. But it needs the ability to be able to go faster than the posted speed limit. I.e if the speed limit is 45mph, going 47mph shouldn't be a problem that the car freaks out over. For a while, on city streets if you were using Autopilot you'd be able to go up to 5mph over the posted limit without issue. I think in the FSD Beta, you can go more.

Can you describe the ruleset that would apply when it’s ok to speed? So that’s applicable to the software of thousands of cars?

The car already has a ruleset for when to not obey speed limits. If you're on the highway and your lane is going 65mph but the other lanes are moving very slowly, the car will slow down accordingly. Similarly, this could be implemented for the inverse to an extent.

And again, I don't think the car should speed by default, but a car going 2-3mph over the posted limit should be acceptable rather than an error state because the world is not black and white.

You're like this close to the the heart of the issue.

If you can determine in real-time whether the maneuver your about to perform or the speed you're going is safe then why even have speed limits? The speed limit for highways is still 65 whether it's a a bone dry, pitch dark, pouring rain, or completely iced over. "Any speed under 65" can't possibly be a safe speed for all these conditions while allowing for the highest safe speeds possible in ideal, or even average, conditions. And this doesn't even being to take into account the huge vehicle variance and tire ware. The safe operating speeds for a top-heavy Honda Fit with narrow tires vs a low-to-the-ground wide-tired Corvette are going to be wildly different.

And then you have to deal with other drivers. If traffic is going 75 you're gonna have a hell of a time merging capped at 65. And in an ideal world nobody would pass on the right making it possible to get off the highway without increasing speed but real life hits hard.

If you can create an all-knowing AI that can predict your the road conditions around a corner or beyond the crest of a hill, maybe. Remember, we are not discussing individual decisions made by people based on a current situation, but the defaults encoded into the software of thousands of cars. And if that default is lax, it will end up in lax behavior.

> Why does the autopilot need to speed to be safe?

For the same reason driving below average speed is dangerous. If you drive 10km/h slower than everyone else you are a problem, even if everyone else is driving at or slightly above the speed limit (very common in Germany).

You are arguing that everyone should be moving faster. But we want everyone moving at the speed limit - building cars that intentionally break the speed limit will make the effective speed creep up. It needs to creep down.

Because you want the flow of the traffic to move with the same speed.

But we want the flow of traffic to be at the speed limit, that’s why there is a speed limit. So more cars need to go slower, not more cars need to go faster.