Earlier quoted context omitted.
You'd still miss out, like with the surgeon's example of a patient calling. It doesn't need a technological solution at all. In the UK and Germany, there were some calls, but it was rare, not even once a month. Do-not-call lists are enforced, and e.g. the ICO can fine directors of companies, not just the companies. Reporting nuisance calls can be done on a website, immediately. Then again, in the US, everything requi…
The UK system is good, but there are still robocalls and scam calls occasionally. If you can make your scam calls from a foreign telephone network with spoofed caller ID, or your scam is good enough you can profitably do it from prepaid anonymous SIMs, regulators claim they're powerless.
I still think privacy laws are more effective. The only time I've had really bad robocalls was when I transferred a domain. Now, ICANN are muppets and wilfully ignore GDPR et al. Okay, so WHOIS "protection", right? But insultingly, transferring domains doesn't work with WHOIS protection, and you need to supply a real number.
(Oh well, at least in the UK I can still buy pre-paid SIM cards with only cash in every major supermarket chain.)