Since the telezapper wasn't a "legal" no solicistors sign it's OK for the telemarketers to avoid it.
As already explained to you, the telezapper merely messes with an automated computer calling system used by telemarketers. As I already said, first, NOT ALL telephone salespeople use those automated systems. Secondly, you're only messing with their system; you're not telling them not to call. (You're thinking in terms of a "group" - not all telemarketing companies are the same. They're not all working the same way, nor do they all know that you have a telezapper).
I notice you continue to ignore the FACT that telemarketers HAVE BEEN required BY LAW to allow people to get off their lists for YEARS and their answer to that was to create convoluted processes most people simply wouldn't have the patience to go through.
And YOU continue to ignore my support of other measures, like fining those particular telemarketing companies who overstep the boundaries and harrass people. Or you as the call receiver able to punch a number that traces the call through the phone company and reports it for harrassment. (And of course there's always you who can tell them to "get lost" and hangup). There are many other possibilities without asking the feds to create a list and then fine every salesperson who makes that first cold call.
It doesn't stop ALL sales people, and it only stops the phonecall as first contact, customers can still request information from the company via male or phone call and work from there.
And, sales for those companies will drop. The reason we receive sales calls is that people are buying from those telemarketers. Those cold calls move potential customers into action; otherwise, the customer might never get around to picking up the phone and calling, and, if he/she does, he/she may call a competitor who will be certain to ensure that the customer doesn't trust the competition.
Again, like it or not, telemarketing, as annoying as everyone finds it, has been a successful business tool. This law outlaws the use of that tool. ("Order-taking" and "following up on a sales call" are not the same as "telemarketing/telephone sales", which are generating much more business than people would like to acknowledge).