Even if the code is flawless now, all it takes is a single flawed line of new code. This is of course true for all languages, but type safety helps a lot as some types of flaws would not compile.
If you have to explain that much about your story, it just means that you weren't able to show your story (or universe). So it's either not a good story or you're not a good writer. After all, we call them "TV shows", not "TV explains". And it had strong "it was just a dream/wasn't real" vibes.
I was using the wording of OP who seems to be talking about tokens. The service asks the trusted entity if the token is valid, the trusted entity deletes the token after the first time.
Making the certs short-lived (a few minutes) and single use and having a rate limit for users could make it difficult enough with serious risks (if you make it a crime) for little profit (I doubt many kids will pay serious amounts of money to watch porn; definetly not drug-scale amounts of money).
Sold by whom? The created cert can be time limited and single use, so the service couldn't really sell them. You could rate limit how many certs users can create and obviously make it illegal to share them in order to deter people from using them. That's not enough to prevent it completetly, but should be an improvement for the use cases I hear the most about: social media (because it reduces the network effect) and porn (because kids will at least know that they're doing some real shady shit).
7.797 (most of them probably interesting movies, series, albums).
I just found out how to put them all in a list and ordered them by age - the oldest ones are from 2003. IMDB is the sixth-oldest. Another intersting old one is https://brickfilms.com/.
I thought the two genders were non-binary and binary?