> 36 billion ads needing review annually

This would mean every single user gets 10 uniquely personalized ads per year.

Even if that wasn't hilariously unreasonable by several orders of magnitude, if the moderation cost was was included in the cost of serving ads, this would all self regulate and only serious actors would participate. Treating it as a public bulletin board while still raking in a percentage of the impressions for sure is a nice business model, but not what's best for the rest of the society. Maybe ads just shouldn't be such a lucrative business.