Europe has a larger population compared to US, yet it has a lesser amount of land to cover with cell sites.
As a result, people/tower ratio is quite good in Europe and partially contributes to better plans.
You have your own answer... if it is the most sparsely populated country, then it needs the fewest towers which also means the least infrastructure investment.
As long as the company providing coverage has other markets (to take advantage of the bulk buying of equipment and leveraging of technology staff), then this becomes an "incremental expense" to them.
I suspect it would be different pricing if a cell company was trying to exist only in this market. But, I digress...
"Engineering without management is art." -- Jeff Johnson