Just whitelist the caller ID and have the originating network guarantor

The second part is the hard part and requires coordination

It wouldn’t be expensive or especially hard to do but there is no payoff for the network. Remember they make money off scam calls too

Since as long as I can remember these organisations have been optimised for profit, not for GAF and that’s why they’re being savaged by regulation and OTT competitors now

There has been no market forces compelling them to do this and until recently when it got really bad, no political or regulatory forces

tl;dr na bro