Second, you are wrong. Medium cities are just like the big cities except without the metro system. Trams and busses are just as good and effective, and the metro is not needed (I hope the reason why not is obvious). Also, here in Austria at least, the trains are really good, really fast, and really, really frequent, and you can just take the metro to the big city center with the same ticket (something you can't do with cars, because cars are not allowed in the center).
Very small towns and don't need public transport because it takes 10 minute to cross them by foot.
This notion that you need a car to move around town or buy groceries is an american concept and seems preposterous to us, europeans. Cars have their uses, obviously, but these are not their primary use here.