Creating a whitelist service for yourself literally only takes a couple hours studying Twilio docs. Hardly a huge waste of time, and when you get 2 spam calls every morning before 8 am for weeks it's completely worth it.
Just imagine you would be in charge to keep your whole town clean of robocalls. What would you do? Set this up for everybody in town, administer it and take care that it's up 24/7?
Helping (anywhere in the line of this process) to pass a law that simply prohibits such calls seems to be more efficient.
Making something illegal doesn't mean it goes away completely (or at all). https://www.consumer.ftc.gov/articles/0259-robocalls#legal