I do not understand really how the companies negotiate to get HD signals for their channels. I often travel and stay at various hotels and they have their TV on in their resting area. I notice as an example HLN (CNN Headline News) in the morning is in HD on Comcast & DirecTV but on FIOS no chance -- they say it is not available as per the channel company. HD signals have been around for years now it should not be a la carte -- I really getting tired of companies earning yearly huge profits on the customers and yet do not really try hard enough to give us every HD that we should be entitled to. Sorry had to vent this!
They all have a limited number of slots available. Each provider can choose what they want to carry.
Verizon is one of the few that carry all of HBO/Cinemax in HD.