I think it's rather that OSA actually visibly affects people in their day-to-day lives whereas other laws don't. I constantly hit age verification pages on Reddit and Twitter and I don't use either for porn. I'm fundamentally against giving Reddit or Twitter or a 3rd party processor my ID just to view content someone somewhere deemed potentially harmful to minors. At least Twitter is done on a post-by-post basis; on Reddit entire subreddits are gated behind age verification.