i'm jealous of you. I recently had a day where I got 25 phone calls. 23 were spam. Turning on iOS "ignore unrecognize phone numbers" has been amazing (i assume android has the same feature)
Almost all spam is instantly recognisable. Mostly visa and parcel delivery scams.
In do not block unknown numbers because lots of organisations use them here (UK) This includes people I really do want to be able to contact me if they want to such as the police.
I think it's mostly just an issue in the US/North America