You can actually design roads to encourage attentiveness - by using road trees, narrower lanes, roundabouts, non-straight roads, or obstacles like bollards or similar. These aren't popular though because people want generally want to zone out and move fast.
Courteousness is a bit more difficult to address with just road / public space design, but designing to encourage more driver / non-driver interaction can help.
edit: a very non-american way to force people to pay attention on country roads is to make them BARELY wide enough to accommodate two cars. This forces attentiveness, because you don't want a head-on collision. Sounds problematic, but actually kinda nice in practice.