> I found myself routinely on roads marked 100km/h that couldn't safely accommodate two cars.
It's worthwhile pointing out that it's fairly normal outside of built up areas in Europe to just have a standard speed limit (often 100 km/h) apply regardless of road conditions: it's simply down to the driver to drive to the conditions. There's plenty of roads around here where you'll struggle to do 30km/h safely, but legally it's 100km/h limit; my experience in various parts of the US would suggest they'd probably have a 30km/h or lower limit there.
I'm surprised you found so many roads that couldn't safely accommodate two cars on any significant route, though!
It's worthwhile pointing out that it's fairly normal outside of built up areas in Europe to just have a standard speed limit (often 100 km/h) apply regardless of road conditions: it's simply down to the driver to drive to the conditions. There's plenty of roads around here where you'll struggle to do 30km/h safely, but legally it's 100km/h limit; my experience in various parts of the US would suggest they'd probably have a 30km/h or lower limit there.
I'm surprised you found so many roads that couldn't safely accommodate two cars on any significant route, though!