They have billboards but they're generally ads for actual products and not a plea to not smoke meth and molest your daughter or saying that Satan rules America because we're murdering innocent babies.

In most of the EU at least, generally not on roadways I believe. Definitely banned on roadways in my mom's country. In countries where they are more common, it's all stuff like [car brand], [museum/landmark near you], [tv network], [unoffensive mainstream political ad], a lot of which is still annoying but preferable to [strip joint at exit], [call shady lawyer now], [repent or burn], [i'm mclovin' it]

The billboards in this photo would be unthinkable anywhere else

Canada does, but for the most part it's just boring advertising and not the wacky shit you get down in the states. You occasionally get an anti-abortion billboard but nothing as intense as what you see down south. Although I used to work for a guy who put up a whole bunch of anti-abortion and pro-trump signs on his land along a highway, including a whole fake graveyard for the unborn babies. Same dude flew a Confederate flag in his backyard