The really smaller villages in the mountains are only connected by postal bus. The villages in the valley and what I could call small towns are connected by train, but it is far from ubiquitous.
True, the density gets much lower in the villages and especially those in the mountains. But for the average person in _most_ of the Swiss villages there is some connection they can take to get to where they need to go (though it may not always be the fastest, depending on where you live)