That's my current experience. Comcast is very fast and low latency. The next best is DSL that maxes out at 2 Mbps. After that my only choice would be some form of wireless.
So if Comcast decides not to sell me service, I'm screwed. They could charge as much as they want and to a point I'd just have to suck it up and pay. I assume the reason it isn't multiple times more expensive is because there is some regulation from the PUC capping what they can charge.
You have ISP #1, who have relatively modern infrastructure and bandwidth.
You may or may not have ISP #2, who have antiquated infrastructure they don't maintain that delivers bandwidth circa 2005.
You probably also have ISP #3, who use alternate delivery technologies (wimax, satellite, etc) to deliver low bandwidth at exorbitant prices.