They aren’t the same thing. With ads the monetization strategy is to implement ads to annoy the user into paying. Then finally paying for it is letting them know that they succeeded in implementing ads in a way that got you to give them money. You are thus incentivizing an ad driven internet.

Paying for access is paying for the service because you think it is good enough to spend money on. This is incentivizing the development of a good service.

Data harvesting another matter entirely. TikTok is going to harvest the data of paying customers and free customers regardless.