I haven't been in houses in all European countries, but I've seen both. I think a range is cheaper (one appliance, one electrical connection), so you find it in cheaper apartments, cheap rentals etc. It might also be the only reasonable option if the kitchen is small.

A separate oven and hob usually means the oven isn't at knee height, which is much nicer. Decent apartments and houses in Europe have this, but so does my relative's million dollar house in the US.

Yes, I have one of these $50 portable cooktops and it works OK but still takes forever to boil water. The expensive ones are actually as good as gas and I was pricing out the freestanding stove+oven, thanks for backing me up xD