In Brazil no one uses common phone lines anymore because, in part, of the telemarketers and scams calls. Most people I know enable “silence unknown callers” and use almost exclusively Whatsapp for communication.
The government tried to control this with an official (no call list) that is usually ignored by companies who use third parties and disposable mobile numbers to do their dirty work.
Telcos have the power to control that but they are usually an internal mess and this is low in their priority list as they consider the voice calls a lost battleground.
ANATEL says we will have authenticated numbers by 2028. After that, it's a matter of pressuring the government to punish the people doing the undesired calls.
The second implementation (AFAIK, we are in the 3rd now) of that no-call list was quite successful in pressuring companies. It can be done.
The government tried to control this with an official (no call list) that is usually ignored by companies who use third parties and disposable mobile numbers to do their dirty work.
Telcos have the power to control that but they are usually an internal mess and this is low in their priority list as they consider the voice calls a lost battleground.