But if you leave that process in the hands of CLEC (telecom providers) they have a financial incentive to make the process impossible and expensive to drive customers away from cheaper alternatives like VOIP.

And the spoofing has become an endemic part of the system. Years ago, there was a separate system for phones, which is why phones kept working even when power an internet went out. That also meant the phone companies knew exactly where a call was coming from because the wire could be traced to its physical location and verified for CallerID. It was also accurate because all landlines were published unless you paid to be excluded.

But none of that is true anymore. Even when you make a call from most "landlines" these days, there's no actual landline phone system it's coming through. It's VOIP. And the same system that's used to identify your number can be used by anyone, and the phone company giving priority to certain carriers and customer as "trusted" while denying it to others raises net neutrality concerns.

It's the ongoing security vs freedom debate. You can't say the phone companies should block calls from unverified numbers while at the same time saying Google shouldn't block download of unverified apps.