Putting someone in federal prison for 10yrs over making $100 is wild. IF they were the ones orchestrating the entire scam, and kept the full $10k+, sure, but they are not. You'll find an endless stream of mules willing to do this kind of work, nothing will happen targeting those kind of people.
The alternative to legally persecuting scammers is legally
not persecuting scammers. Which is unacceptable as far as I'm concerned. You may as well feed your grandpa to the wolves.
edit: As to nothing happening, well, I disagree. Sure, some people will continue, but many won't.
I struggle to see how its not exactly the same as targeting low level drug users or dealers.
What's wrong with persecuting drug dealers? They are the scum of the Earth, knowingly causing wholesale misery by means of distributing awful illegal shit.
I don't have a simple solution for you, other than whats been mentioned: reduce calls coming in via technological means.
Reduction of calls is all well and good, but there are other non-call methods available and commonly done, ranging from simple cons to fairly complex gray areas, where elderly people are
not herded, but rather
invited to an event and they are not forced to buy the awesome and obscenely expensive set of pots, but surely they only want only what's best for their grandchildren, right? With a paper invite bulk delivered to an old folks house mail box.
I know I may have a simplistic view of the world, but I simply find a vision of the world where my grandma, who's never in her life done anything but be nice to people, will find herself scammed out of her life savings or even her flat due to some dick randomly picking her phone number appalling. I have no sympathy for that sort of scum.