I agree with you, these people hide behind their phone. I put all our numbers on the Do Not Call Registry, and does no good. I am reporting them to the FCC. Just go to www.FCC.org and report them.
Also, DNC registry only applies to people who follow the law. Criminal scammers are going for much bigger loot, like getting your credit card number or identity. Why would they let a little telemarketing violation stop them? Plus, many of these operations are located outside of the U.S., where they're out of reach of our laws. It's so easy to fake caller IDs so that you can't tell.