(Adapted from a deeply-nested too-late-to-notice reply I made on another thread[1], but which I suspect more people would benefit from seeing)

I am skeptical that AIs capable of piloting fully driverless cars are coming in the next few years. In the longer term, I'm more optimistic. There are definitely some fundamental breakthroughs which are needed (with regards to causal reasoning etc.) before "full autonomy" can happen -- but a lot of money and creativity is being thrown at these problems, and although none of us will know how hard the Hard problem is until after it's been solved, my hunch is that it will yield within this generation.

But I think that framing this as an AI problem is not really correct in the first place.

Currently car accidents kill about 1.3 million people per year. Given current driving standards, a lot of these fatalities are "inevitable". For example: many real-world car-based trolley problems involve driving around a blind curve too fast to react to what's on the other side. You suddenly encounter an array of obstacles: which one do you choose to hit? Or do you (in some cases) minimise global harm by driving yourself off the road? Faced with these kind of choices, people say "oh, that's easy -- you can instruct autonomous cars to not drive around blind curves faster than they can react". But in that case, the autonomous car just goes from being the thing that does the hitting to the thing that gets hit (by a human). Either way, people gonna die -- not due to a specific fault in how individual vehicles are controlled, but due to collective flaws in the entire premise of automotive infrastructure.

So the problem is that no matter how good the AIs get, as long as they have to interact with humans in any way, they're still going to kill a fair number of people. I sympathise quite a lot with Musk's utilitarian point of view: if AIs are merely better humans, then it shouldn't matter that they still kill a lot of people; the fact that they kill meaningfully fewer people ought to be good enough to prefer them. If this is the basis for fostering a "climate of acceptance" then I don't think it would be a bad thing at all.

But I don't expect social or legal systems to adopt a pragmatic utilitarian ethos anytime soon!

One barrier it that even apart from the sensational aspect of autonomous-vehicle accidents, it's possible to do so much critiquing of them. When a human driver encounters a real-world trolley problem, they generally freeze up, overcorrect, or do something else that doesn't involve much careful calculation. So shit happens, some poor SOB is liable for it, and there's no black-box to audit.

In contrast, when an autonomous vehicle kills someone, there will be a cool, calculated, auditable trail of decision-making which led to that outcome. The impulse to second-guess the AV's reasoning -- by regulators, lawyers, politicians, and competitors -- will be irresistible. To the extent that this fosters actual safety improvements, it's certainly a good thing. But it can be really hard to make even honest critiques of these things, because any suggested change needs to be tested against a near-infinite number of scenarios -- and in any case, not all of the critiques will be honest. This will be a huge barrier to adoption.

Another barrier is that people's attitudes towards AVs can change how safe they are. Tesla has real data showing that Autopilot makes driving significantly safer. This data isn't wrong. The problem is that this was from a time when Autopilot was being used by people who were relatively uncomfortable with it. This meant that it was being used correctly -- as a second pair of eyes, augmenting those of the driver. That's fine: it's analogous to an aircraft Autopilot when used like that. But the more comfortable people become with Autopilot -- to the point where they start taking naps or climbing into the back seat -- the less safe it becomes. This is the bane of Level 2 and 3 automation: a feedback loop where increasing AV safety/reliability leads to decreasing human attentiveness, leading (perhaps) to a paradoxical overall decrease in safety and reliability.

Even Level 4 and 5 automation isn't immune from this kind of feedback loop. It's just externalised: drivers in Mountain View learned that they could drive more aggressively around the Google AVs, which would always give way to avoid a collision. So safer AI driving has led to more dangerous human driving.

So my contention is that while the the AVs may become "good enough" anytime between, say, now and 20 years from now -- the above sort of problems will be persistent barriers to adoption. These problems can be boiled down to a single word: humans. As long as AVs share a (high-speed) domain with humans, there will be a lot of fatalities, and the AVs will take the blame for this (since humans aren't black-boxed).

Nonetheless, I think we will see AVs become very prominent. Here's how:

1. Initially, small networks of low-speed (~12mph) Level-4 AVs operating in mixed environments, generally restricted to campus environments, pedestrianised town centres, etc. At that speed, it's possible to operate safely around humans even with reasonably stupid AIs. Think Easymile, 2getthere, and others.

2. These networks will become joined-up by fully-segregated higher-speed AV-only right-of-ways, either on existing motorways or in new types of infrastructure (think the Boring Company).

3. As these AVs take a greater mode-share, cities will incrementally convert roads into either mixed low-speed or exclusive high-speed. Development patterns will adapt accordingly. It will be a slow process, but after (say) 40-50 years, the cities will be more or less fully autonomous (with most of the streets being low-speed and heavily shared with pedestrians and bicyclists).

Note that this scenario is largely insensitive to AI advances, because the real problem that needs to be solved is at the point of human interface.

1: https://news.ycombinator.com/item?id=17170739