How would you know if the paid version is privacy respecting or not? If for example FB had a 5$/mo subscription that was ad free, how would you know that access to your database wasn't still being sold?
For me that kind of problem is the blocker, and "oh look nobody paid for for the premium version, therefore people don't value privacy" is a bit disingenuous.
If you are buying a product/service and it says it won't do something (like sell your data) and does anyway, that's clearly wrong. They agreed to protect your privacy. With services that state they will use your data to run targeted ads you are immediately accepting the loss of privacy.
"clearly wrong" means nothing if you can't win a law suit against megacorp's carefully worded legalese. "We use this information to improve the Service" means game over.
What if there were a trusted third-party that periodically audited the business to see if they were protecting your privacy of not. Would people value or trust that? And who would people trust to do the audit?
For me that kind of problem is the blocker, and "oh look nobody paid for for the premium version, therefore people don't value privacy" is a bit disingenuous.