But that's not even the biggest problem, the biggest problem is that it is trivial to spoof caller IDs in the US, and many of those operators do just that.
So tracking down who actually called can be tricky, then even if you could you still need to either get them extradited for robocalls (which isn't happening) or get them prosecuted abroad for breaking US law (which, again, isn't happening).
I personally feel like it can be solved however it has to be solved like this:
- Eliminated caller ID spoofing through technical means.
- Once caller ID is accurate, you can both have apps/databases with known bad callers or callers from VoIP providers, and or you could fine the VoIP providers facilitating this type of activity in the US (i.e. give them a motivation to stop abusive behaviour on their services).
I mean heck, if a VoIP limited each account to just ten calls per minute, it would massively decrease the volume of robocalls overnight. But none do because they have a financial motivation to keep allowing these companies to operate on their services and zero motivation to stop them (since it is almost untraceable anyway).