ADSL lines are generally twisted pairs, which reduces radiation immensely. AFAIK, ADSL operates at lower frequencies and lower power levels than BPL, which also works to reduce interference potential.

The amateur bands are located where they are as a result of international treaties. It would literally take more than an "Act of Congress" to reallocate them. Domestic television and cell phones don't span the globe, and are primarily regulated at a national, not international level.

There are many digital modes employed in amateur radio. But mandating a shift to digital technologies here would eliminate much of the ability for hams to get on the air quickly in emergencies using low cost or even homebrew equipment. It would also price ham radio out of the reach of most youngsters. We would lose a lot when you could no longer communicate with a simple oscillator and crystal detector.

Besides, hams were here first! [Linked Image]