Of course, one could argue, is the Federal Governments' place to impose what technologies must be utilized in the broadcast spectrum? They can govern portion of the bandwidth, but should they be able to force adoption of a particular standard?
You are correct they do own the airways and allocate the bandwidths to the different services. By going digital they will free up much other needed bandwidth for other services. Digital video uses less bandwidth but has to be compressed because video has a lot of information. Kinda like why we zip up files when we send documents on emails that are large.
OK, what I don't understand is, if your TV already can receive digital signals through a cable hookup, WHY do you need a converter box to get pictures over the air?
Composite video outputs, s-video outputs, component video ouputs on cable boxes are all analog signals which can feed your TV
Most digital cable boxes have these analog outputs which can feed any TV
The newer cable boxes add DVI (digital video, but analog audio) and HDMI(audio/video digitally encrypted) are all digital outputs.
Your analog only TV cannot received these inputs but the newer HD TV's can and the picture looks great.
The new converter box will pick up digital signals and convert them to an analog signal your old analog TV can receive.
The newer HD TV's already had this HD tuner built in so they can received them off of the air or from a cable box with a DVI or HDMI output.
I hope this explains it.