Part of the reason the telecoms in the US were slow to upgrade was that they were originally forced to do local loop unbundling. Why invest if competitors could use those lines for cheap rates?

And the cable companies already had a high bandwidth (at least for ~2000) transmission line to most houses in America.

Notably, Verizon tried with FIOS, but it wasn't that profitable. Most people stuck with cable internet, even if it was slower.