These folks include presenting a false person as being of age, then switching to underage at the time of meetup when the target shows up.

I’ve never seen even a single instance in my own viewership of numerous channels that engage in pedophile hunting where the person is presented as being above the legal age of consent, then only switching to underage at the time of the meeting. They’re presented as underage from the get-go.

Then the group tries to kill the person

Again, this doesn’t seem to be a widespread thing compared to the number of them that simply lure them to a location then ask them questions (and directly state that they are free to leave at any time since they’re not law enforcement and can’t arrest them) The people you’re talking about are a small minority of both the actual number of pedo hunters, and the number of overall views received.

And the perpetrators think this is justice.

I doubt the people that are explicitly lying to farm content think it’s justice. I do believe the people actually catching people who voluntarily contacted someone presented as underage from the start do.