Anyway, as a simple test try and count how many cars you can see next time you go for a drive, how many people’s gender you can infer, and how many you can positively identify based on their looks. It’s significantly safer to try this as a passenger.

Might be interesting to try, but I think in a situation where I notice a bad driver I'm much more likely to identify their gender than in a random passing car.

But I live in a comparatively small Austrian city riddled with traffic lights, weird intersections, crosswalks, and way too much traffic in general, so I get ample opportunity to look at slow moving cars. If you're American your culture around cars is probably very different and that might explain why we seem to have a different intuition about this.