This is enabled by essentially free communication --- while it's probably not feasible to go back to the rates Ma Bell used to charge so as to fund their infrastructure (and generous pensions, and stock dividends)....
Why not have a system where a small amount of money is put in escrow when a call is placed? If the person who answered the call is displeased by it, they can punch in a command at the keypad after the call to claim the money.
Because phone operators make money on all those robocalls, and have so far decided they'll make more money allowing it, than trying to obstruct it.
And, I mean, what are you going to do? Change your phone operator? They're all the same. Switch to using WhatsApp/Signal/etc. for calls? Sure, but you're still paying some telco for the mobile data plan.
That's the problem: all the actors with leverage here are happily making money on the scheme; regular customers... have no leverage.
Why not have a system where a small amount of money is put in escrow when a call is placed? If the person who answered the call is displeased by it, they can punch in a command at the keypad after the call to claim the money.