

couldn’t they just run down the registered sex offender list
The point of their channels is usually to find new predators that haven’t been caught, so they can then face legal consequences, (or at least be pushed to stop acting on their desires) rather than to punish people for being pedophiles in general, so it wouldn’t really make sense to go after those who were already convicted.
It depends on how these channels are going about finding their victims for it to be considered similar.
Remember, entrapment is based around luring someone to do something they otherwise would not have done had the operation to entrap them not occurred. If they created an account posing as a minor, then directly DM’d a person asking if they wanted to do x/y/z with a minor, that would be entrapment.
But if they made an account claiming to be a minor on social media, and the person contacted them voluntarily, asked their age, was told it was under 18 and still continued messaging, then sent explicit photos, that’s not entrapment.
However, if they were then the people who initiated the conversation about wanting the person to come to their house / visit them somewhere, that could be considered entrapment, and the only evidence against the person that could be eligible for use in court would be the explicit material they sent without being prompted.
It varies case-by-case, but from what I’ve seen, most of the larger operations tend to try and avoid entrapment-like tactics in most cases, where they only allow the other person to initiate unlawful behaviors, rather than prompting anything themselves.