I've posted this on a previous robocall thread. Some don't understand the complexity of this issue. It's not (only) the carriers' fault:
Why do you think this is the carriers' fault? They have to follow FCC regulations:
https://www.consumerreports.org/robocalls/block-robocalls-new-fcc-rules/
Excerpts from the article: my emphasis of the text in BOLD
The Federal Communications Commission voted on Nov. 16 to
allow telephone carriers to block robocalls that appear to be fraudulent—a particularly annoying and costly problem that has mushroomed in recent years.
Mahoney says Thursday's decision by the FCC is a step in the right direction, but she points out that only a small percentage of the calls will end up being blocked.
The FCC's ruling comes partly in response to a request from
the telecommunications industry, which wanted to know whether it could block calls without breaking federal call completion rules, which bar phone companies from call blocking without customer authorization.