It was the case in France too, it was called Bloctel; you just had to register your phone number and telemarketing companies had a legal obligation to look it up and not call you.
So it worked for a time, legit companies stoped calling; however most people didn't knew about Bloctel as it was little advertised.
Meanwhile, spam calls turned into scam calls, and a real issue especially with the elderly.
So I think that banning all unsolicited calling kills two birds with one stone, spam becomes illegal and scams as a consequence becomes easier to spot as there are no more unsolicited calls.
We have that kind of list in Italy too. I registered my number and I keep getting calls, so I stopped answering to numbers not in my contacts list. If I know that somebody will be calling me, I ask for the number and I add it to the list.
Have you tried answering and then just saying the name of the list you've enrolled in? Tends to help propagate to the companies that they absolutely should not call the number again. At least here the companies tend to actively self-moderate and cross-reference against the lists, as the law does get enforced. When I worked in cold-calling call centers in the past, I remember they being strict with teaching the "marketers" what to do when people brought up the local list(s).
So it worked for a time, legit companies stoped calling; however most people didn't knew about Bloctel as it was little advertised.
Meanwhile, spam calls turned into scam calls, and a real issue especially with the elderly.
So I think that banning all unsolicited calling kills two birds with one stone, spam becomes illegal and scams as a consequence becomes easier to spot as there are no more unsolicited calls.