the simple truth is that it's far easier to wire a small country than it is to wire a large county.
If you have a high population density you also have the ability to spread the cost of doing so across many more people.
and frankly, it helps to be late to the party as you only have to implement the latest and best technology, not each generation as it is developed (never mind paying the cost of the development)
the result is that in small, high population density countries you can have really good infrastructure, but in larger areas you aren't going to have nearly as goon an infrastructure, not matter what the cost.
I live in the greater Los Angeles area, but out around the edge of it. I pay $130/month for 1.5Mb down/768Kb up. I could upgrade to an ethernet connection up to 5Mb, but then it would cost me $100 per Mb.
and I'm in a 'good' (but not 'great') area for connectivity. Where my sister lives, their only option is satellite (with a ~1000 ms first hop ping time) to give you an idea of how remote they are, they literally live 20 miles from the nearest fast food place.
now there are places in the US with connectivity almost as good as what you get (although at higher out-of-pocket costs, I'm assuming that your system has some tax money included in it), and I wouldn't lay a bet either way on if there is more area covered with such good coverage in the US vs in Sweden, but it could be several multiples larger in the US and not make a significant dent in the problem.