I'm always flabbergasted at seeing how these things are handled in America.

Long ago in the country where I live, the regulator:

- set up an opt-out central register where the owner of any phone number can freely declare they do not want any unsollicited calls

- made this register freely available to all businesses

- required from telcos that they make it easy for customers to report infringing calls

- made telcos liable if they do not swiftly take action whenever they have 'sufficient' reports (10s not 1000s) that one of their clients is infringing on the opt-out list, including by cutting off all of the client's numbers.

... does not seem such a big deal to set up.