This is putting a bandaid on a rotten leg. What is needed is a way to stop businesses from calling you if you haven't given them permission. It is a huge problem in the US but it isn't like this everywhere. The underlying problems should be fixed instead: Laws that actually prevent this (enforced laws) and the opportunity to block non-local calls from places not as functional (like calls from the US).
I have had the same mobile phone number for decades and I get maybe one call a year from a business that I haven't specifically allowed or requested calling me and it is always international because local laws actually work.
Yes, it is a band aid, or one solution out of many needed ones, and yes, probably not highest priority in terms of needs. But it doesn't have to be a either...or...
And I wouldn't derive from your lack of need from a lack of need for others!! Independently from the country. Stealing is allowed in no country, and it still happens in every country. Laws and enforcement is great, but it won't stop 100% cases, and if I like to have a door lock on my door (or two), then let me do... I don't care if some don't feel a need for it (and stealing is just an example... the same for so many illegal things).
I have had the same mobile phone number for decades and I get maybe one call a year from a business that I haven't specifically allowed or requested calling me and it is always international because local laws actually work.