there seems to be enough exceptions to make the law almost useless.

I don't think so, as most of those companies are not where the bulk of my calls come from. I agree, however, that I see no reason for an airline to call unless you were doing business with them already (which is already exempt anyway). Perhaps this is just more of the "lets help out the airline industry" stuff?

Now they just need a "do not knock on my door" registry.