A working legislature?

Don't know about Europe, in Brazil spam calls are common but you can register your number in a consumer protection organ to say that you do not want unwanted commercial calls and if you keep receiving them the companies can be fined, for me it works "ok", there still companies that don't give a shit but at least the amount of calls I receive was reduced a lot...

* Not directly related to SPIT (phone SPAM), but one is https://www.wired.com/story/sim-swap-fix-carriers-banks/ .

* Carrier maintainer blacklists and other tools have also been used by providers for a long time.

* My provider, Voip.ms, enforces a provenance whitelist by default. This block all SPIT calls coming from unspoofed caller ids. That may not sound like a lot, but yes, many of those calls are just random poeple picking their phone or mobile apps using the real phone number. Having regulation to track internal sources of SPIT (and enforcing it) helps too.

* In Canada, you can subscribe to a non-telemarketing list. That doesn't help for scammer, but it helps for unsolicited ads, political spam and private surveys. This works when enforced with actual penalties for all parties involved.