Why does Comcast Not use LMR400 if it's such low loss?

[StormyNitesOnCB]

1.) Why does Comcast Not use LMR400 if it's such low loss?
2.) What is the loss factor on the Coax Comcast uses?
for HDTV and Hi-Speed Internet I would assume it has to be a Low Loss Coax.
3.) Is there better stuff they could use for their application but their just cheap and cutting cost?