If one needs excuses to justify having a car and being stuck in traffic, hills ain't a valid one. 30km/h is great, makes for less noise, less air pollution, and now we see, it makes it for 0 traffic deaths. Much better to have the option to reach a grocery store on foot, by bike, by public transport and car than have no options but a car. That makes for less cars on the road, and, funnily enough, 30km/h on a non-busy road will often get you faster to where you want to go than 50 on a busy one.

Again, that's why we Europeans are both happier and fitter than our American counterparts.