I wouldn't call our playgrounds protected. They had driveways between the actual buildings and the playground, and cars went there occasionally. But the drivers were generally well aware that there'd be kids around, and drive carefully there.

Sidewalks, yeah, I'll grant you that. It's still the thing that amazes me most about US - that so many roads here plainly don't have any sidewalks. I'm used to seeing them on literally every road that is in a populated area. Even villages usually had them!