Earlier quoted context omitted.
It's not that the bandwidth is expensive; it's the cost to deploy everything. If there was preexisting conduit/fiber in the ground and all we had to do was plug two cables together, I'd be able to charge $25/m too. I've never been to the UK, but I believe your population density is a lot higher than that of the US; which is where all of our costs originate (interconnecting the customer to our network).
I don't think that's the reason really. The main reason I can see is that Comcast (or cable internet) has no real competition. I don't understand why that is. AT&T, Verizon etc seem to have given up on competing. Verizon stopped their rollout of FTTH a while back nearly entirely, though it has restarted very slowly. AT&Ts VDSL based UVerse solution is way too sparse, with very long cable runs. Compare this to BT in t…
The Telco can offer a few things like fiber connectivity between county buildings, tax payments, etc. By doing that, they secure the rights to the area. Given the federal system of the United States, this is a difficult thing to stop.
This makes true market-based competition within most areas very difficult to achieve.