I'm going to mangle the terms of art here, but the ur-problem is that labels of routing, like phone numbers and email addresses, get confused with labels of identity, and then with indicators of trustworthiness.

Everything is built to address that weakness - think DKIM, SPF, etc, plus STIR/SHAKEN, to say nothing of IP or ASN filtering, but they feel like bandaids on a very difficult problem. What you end up with are basically default-deny except for a personally curated trust set ("only accept calls from my contacts", "everything goes in spam unless I have previously corresponded with the sender"), etc.

One last robocall story. AT&T sat on their hands for years until consumer groups embarrassed the then-CEO enough to do something about it. There was a memorable interview in the Dallas Morning News where they called him on it instead of lobbing him softballs and I suspect that the embarrassment finally got through.