You think "people are switching away from using the traditional phone system entirely" isn't enough incentive? And how, exactly, does an Indian scammer paying a bill to an Indian telco incentivize US telcos to drag their feet? You can blame the Indian telcos, but they also don't have incentives to tolerate scammers--their business would benefit a lot more if calls from Indian numbers weren't automatically assumed to be scams.

While you don't understand the problem, you can't possibly have anything of value to say about the solution.

There may well be perverse incentives causing certain entities to tolerate scammers, but we shouldn't pretend we know what those perverse incentives are when we can't even trace the calls. On the other hand, it is much more likely that once the spoofing problem is solved, the incentives are all already in place and the vast majority of scam calls will be solved.

If a rational person only knows how to use a hammer, they pause when they come across a problem that isn't a nail. But when the HN crowd comes across a problem that isn't immediately solved by incentives, they argue that the people who actually are qualified to solve the problem with other tools, should be using incentives!