Yes but if you compare urban areas (where 80% of people live in both continents) in US and Europe it's not massively different (Europe maybe 2-4 more dense depending on the country/city).

Obviously you're not going to lay fibre to the last 1% of population in the US (for the most part).

As one of the last 1% of population with fiber, your take on population stats in the US is wildly off.