The effect of density is not overstated. States' average bandwidth in the Akamai rankings line up closely with population density. I live in Maryland (one of the most densely populated states, though half the density of the U.K.) and most of the urban areas have fiber available (the exception being Baltimore city, for political reasons).
Even if you live in an urban area, the prevalence of rural areas (and poor urban areas), has an impact on you, because the US supports rural telecommunications through various internal cross-subsidies instead of direct support.
The regulatory regime plays a role too, but it's more complicated than your simplistic presentation. In the U.K., the last mile infrastructure is owned by a single company (BT Openreach), but equally importantly, the government ensures it is a quite profitable company. Much more so than American utilities. That was a conscious part of the BT privatization: designing a rate structure that would ensure prices high enough to create adequate incentives for investment.
Even if you live in an urban area, the prevalence of rural areas (and poor urban areas), has an impact on you, because the US supports rural telecommunications through various internal cross-subsidies instead of direct support.
The regulatory regime plays a role too, but it's more complicated than your simplistic presentation. In the U.K., the last mile infrastructure is owned by a single company (BT Openreach), but equally importantly, the government ensures it is a quite profitable company. Much more so than American utilities. That was a conscious part of the BT privatization: designing a rate structure that would ensure prices high enough to create adequate incentives for investment.