Why isn't everything HD?

Time and money.

For a program to be HD, it must be shot in HD, edited in HD, distributed to the local stations in HD, transmitted to you (over the air, cable, satellite) in HD and you must have an HD set.

Replacing every piece of equipment involved is quite expensive. Also, the equipment usually isn't built until ordered so there can be about 90 days lead time just to get it in house. TV stations and program providers have to budget for this and replace stuff as they have the money to do so. Any piece along the whole chain that has not been upgraded will stop the whole show.

Also, not all programs are produced in HD for the same reasons listed above. Legacy programs were not in HD, either. For example, CSI from 10 years ago will not be in HD when it's rebroadcast (which currently is happening on cable). If a program was not produced in HD, it doesn't matter if the station is HD capable, the show won't be HD.

Time, money, and technical resources. HD involves a lot more "stuff" and spectrum bandwidth than SD. HD will become more common in time, but there simply are not enough technical resources or funding to do them all at once, right away.

And sincere congratulations on being among those on this forum who actually understand that HD and Digital are not the same thing.

(Some great answers here already. Here is mine.)

An estimated 20 million people with standard def televisions still get their programming from an antenna and millions more only have standard def from cable or sat providers.

Since commercials pay for all of television programming - the advertisers dont want to cut these people off by converting to HD.

HDTV can handle standard def shows and commercials - but standard def televisions cannot.