You're comparing London to Middle of Nowhere USA. Gigabit symmetric for $80/month is available all over D.C. (More expensive than London, but incomes here are higher too.)
Yep, live in Middle of Nowhere (ish) UK...I pay £30 for 70mbps, and am very happy. I moved recently from a larger town nearby, there I paid the same price for 20mbps (and it was horrendous service, up/down all day).
I live 20 miles from a fairly large city, there is a gigabit loop there...only high rises, average speeds in the city are 70bmps (which is why I feel lucky, I am right next to an exchange).
The fibre rollout was completely botched in the UK. BT (the former monopoly) was investing in TV and mobile, the govt has caught up with them now (and agreed to CPI+5% rate increases) but all through the 2010s, the only fibre investment was a startup that did a lot but was obviously limited by capital (CityFibre, just acquired by Goldman Sachs...so that should go well). The sector was also gunshy after the fallout from the late 90s: a big company invested heavily in fast internet and tried to overlay BT's network, it got taken to the woodshed.
The only place with consistently fast speeds over 100mbps is a small town/city on the East coast called Hull, due to a quirk of history they are the only place that is outside the BT monopoly (the monopoly there was run by KCom) so they got investment, and pretty much nowhere else did.
I am aware of the issues in the US but the UK is not a good example. As said above, telecoms policy through the whole of the 2010s was seriously mismanaged. We will catch up but we aren't a good example (most of the UK population is densely packed into England, which is the size of Alabama but with over 10x the population...even Scotland, which is roughly the size and population density of Alabama, has 75% of the population in 5% of the land...it shouldn't be hard).
You're comparing London to Middle of Nowhere USA. Gigabit symmetric for $80/month is available all over D.C. (More expensive than London, but incomes here are higher too.)