Because the service providers for post-paid phone accounts are also in the business of re-selling your PII to marketers, probably. You can get a pre-paid with

Because the service providers for post-paid phone accounts are also in the business of re-selling your PII to marketers, probably. You can get a pre-paid with cash in many if not most places. Your identity can probably be deduced from call/text graph analysis, but that's not the same as having the people whom you're paying regularly for the account selling your identity to anyone with a buck to spare.