The phone service providers could absolutely do something about this and the barrage of car warranty calls that consumers are experiencing in record numbers. The reason they do nothing is obvious; there is no financial incentive for them to do so. Until legislation mandates, don't expect anything to change.
Your new phone number is someone else's old number. Your pests may be looking for the previous owner.
Many if not most scam telemarketers use robo-dialers that call every number, even those that are not in service.