Of course I may have simply been lucky, but given that my driving license is valid in many countries it seems as though humanity has determined this is mostly a solved problem. When someone says "Put a Waymo on random road in the world, can it drive it?" they mean: I would expect a human to be able to drive on a random road in the world. And they likely could. Can a Waymo do the same?

I don't know the answer to that one. But if there is one thing that humans are pretty good at it is adaptation to circumstances previously unseen. I am not sure if a Waymo could do the same but it would be a very interesting experiment to find out.

American suburban streets are not representative of driving in most parts of the world. I don't think the bar of 'should be able to drive most places where humans can drive' is all that high and even your average American would adapt pretty quickly to driving in different places. Source: I know plenty of Americans and have seen them drive in lots of countries. Usually it works quite well, though, admittedly, seeing them in Germany was kind of funny.

"Am I hallucinating or did we just get passed by an old lady? And we're doing 85 Mph?"

That's experience and you learned and survived to tell the tale. Its almost as though you are capable of learning how to deal with an unfamiliar environment, and fail safe!

I'm a Brit and have driven across most of Europe, US/CA and a few other places.

Southern Italy eg around Napoli is pretty fraught - around there I find that you need to treat your entire car as an indicator: if you can wedge your car into a traffic stream, you will be let in, mostly without horns blaring. If you sit and wait, you will go grey haired eventually.

In Germania, speed is king. I lived there in the 70s-90s as well as being a visitor recently. The autobahns are insane if you stray out of lane one, the rest of the road system is civilised.

France - mostly like driving around the UK apart from their weird right hand side of the road thing! La Perifique is just as funky as the M25 and La Place du Concorde is a right old laugh. The rest of the country that I have driven is very civilised.

Europe to the right of Italy is pretty safe too. I have to say that across the entirety of Europe, that road signage is very good. The one sign that might confuse any non-European is the white and yellow diamond (we don't have them in the UK). It means that you have priority over an implied "priority to the right". See https://driveeurope.co.uk/2013/02/27/priority-to-the-right/ for a decent explanation.

Roundabouts were invented in the US. In the UK when you are actually on a roundabout you have right of way. However, everyone will behave as though "priorite a la doite" and there will often be a stand off - its hilarious!

In the UK, when someone flashes their headlights at you it generally means "I have seen you and will let you in". That generally surprises foreigners (I once gave a lift to a prospective employee candidate from Poland and he was absolutely aghast at how polite our roads seemed to be). Don't always assume that you will be given space but we are pretty good at "after you".

> My anecdata suggests that Waymo is significantly better than random ridesharing drivers in the US, nowadays.

Those two aren't really related are they? That's one locality and a specific kind of driver. If you picked a random road there is a pretty small chance that road would be one like the one where Waymo is currently rolled out, and where your ridesharing drivers are representative of the general public, they likely are not.