[1] Cell service isn't like an iPhone, where it's made in China wherever you buy it. U.S. cellular providers pay U.S. rents for tower sites and U.S. salaries for the skilled labor to install and maintain them.
Anyway the cheapest list price for unlimited text, talk and data is from Globetel at 22,85€. https://globetel.fi/liittymät
However, nobody pays list prices, there are always specials as the cell phone companies battle each other for market share. The cheapest offer for unlimited and uncapped 4G is currently 2,90€ per month.
What point are you trying to make, other than picking random plans?
I will concede that including discounts make things tricky, even if they are an integral part of the market, but by what measure should MVNOs be overlooked? Unlike in the US, MVNOs in other countries generally have the same access to the network as the MVO service arm.
The fact remains that in Finland you can get a real uncapped and unlimited 4G plan for about twenty bucks. Everything unlimited for under thirty. And capped 4G plans for under ten bucks.
By what measure does the US come even close?
EDIT: for clarification the above prices are all list prices from MVOs, with the exception of the everything unlimited which is from an MVNO. The equivalent MVO plans are a few euro more.
And what's your point? Are you saying that population density is not correlated with cost of broadband infrastructure per capita because there exists an outlier?