Taking these guys to court does require a lot of time and effort, but as far as I know it's the only recourse we have. That said, caller ID works pretty well as a spam filter for me...
My only problem with that is, now, to have an effective block against people I don't want calling me, I have to pay for an additional service, so that I can properly use my service I was already paying for?
Frankly, its far better and more cost efficient, to own a cellphone. As I understand it, telemarketers, polititions, and any other group which uses unsolicited phone calls to push its business aren't allowed to call cell phones (due to the cost levied on the reciever I believe). Thus, I can have a cell phone and hopefully, never recieve any "junk calls" which, luckily, haven't occurred yet.
I definately agree with the parent though, especially because its the only recourse seemingly available. Why in the world do people put up with this crap? Because it is easier to try to ignore it than to deal with it. THAT is what is wrong with the US, not that we have "too many" frivolous lawsuits.