This is actually an easily solvable problem. In fact, most of the world has already solved it by not allowing caller-ID spoofing and by blocking bad actors similar to the way that ISPs block email coming from known bad IPs.
The US has the STIR/SHAKEN authentication protocols, but the telcos seem to have no financial are regulatory pressure to clamp down on all the sketchy intermediate carriers the scammers use to bypass them.
Rather then actually solve the problem, the US prefers to turn it into a business opportunity with the telcos selling subscriptions to blocking software and an entire ecosystem of moderately effective apps.
The US has the STIR/SHAKEN authentication protocols, but the telcos seem to have no financial are regulatory pressure to clamp down on all the sketchy intermediate carriers the scammers use to bypass them.
Rather then actually solve the problem, the US prefers to turn it into a business opportunity with the telcos selling subscriptions to blocking software and an entire ecosystem of moderately effective apps.