The Verizons of the world will skim the cream from the blue zones and ignore the red zones, that's why.
As much as I hate govt regulation, it's going to take an act of Congress (as with electricity and telephone) to make broadband ubiquitous.
There is ample justification because the internet is now a part of the critical infrastructure.
BUMP
Why the presumption that broadband should be ubiquitous? If there's a market, private enterprise will serve it.