Are there any actual dwellings around the road? If so, those speed limits are quite reasonable or even on the high end. In Europe it is 50 km/h (30 mph) if there are houses around a road, and 30 km/h (18 mph) for actual town streets. The streets are also specifically designed to be narrower and there are a lot of traffic calming measures to make drivers naturally want to drive the speed limit. This way it is safe & pleasant for townsfolk to cross the street, the town doesn't end up split in two by the highway, and if you're a sane driver you won't get fined even if you accidentally miss a speed limit sign.

Perhaps the best solution is to make the highways go around towns completely to avoid all of this. (and then we can also work towards banning cars in populated areas)