Outside France people don't live in big clusters. Take a look at the night satellite view. All those small/continuous towns do not have (functional) public transport. In my 12k-people town we don't have buses other than school buses and long-distance ones. And unfortunately people don't really walk other than for leisure.

As far as I know the closest city with public transport counts 100k residents, but there are 60 smaller towns in my province alone.