Interestingly in Spain cyclists are well-protected and ordinary drivers who otherwise might drive pretty unsafely, take care of them. Coming from a different place it's so weird to experience someone driving 35 km/h behind a cyclist on a country road because there is a solid white line and a "no overtake" sign. Even if they do overtake (legally) they always keep at least 1.5 meters. There was a huge awareness campaign about this and it is working.

Is that true? 30 years ago I heard that Spain was notoriously unsafe for cyclists and some car drivers might intentionally endanger or hit cyclists in ways we now hear from the US. If that was true then, and now the attitude in Spain has changed so much, I dare say there's hope for the US as well.

The law protects the cyclist but he/she has much more skin on the game. There are still accidents resulting in deaths and not all find the culprit car.

Note that in Spain it is legal to cross the solid white line to take over a cyclist.

Sure, It is sometimes annoying but having more cars would also created more traffic.