Technology

You are working under the assumption that these "pedo hunter" groups are all acting in good faith and on good information. I encourage you to do some reading. There are many cases where these groups pretend to be 18 year olds, lure an unsuspecting person into a meeting, and then lie to their audience about the age they originally claimed to be online, as Xatolos has pointed out.

Lots of them do it to lure in and attack LGBTQ+ folks, while others act on false accusations they receive from third parties:

Innocent dad tortured and killed by group of chainsaw-wielding ‘paedophile hunters’
A gang of vigilantes tortured and killed a father of eight as they tried to force a confession out of him for crimes he didn't commit.
The case of the brutal torture and murder of Bradley 'BJ' Lyons, which shook Australia in December 2018, is once again under the spotlight as a jury has brought to justice the gang leader, Albert Thorn, and some of his mates who helped during the hideous attack.
Mr Lyons was referred to the gang by his wife Jana Hooper, who had falsely accused her husband of sexually assaulting two of her teenage daughters.
Thorn, the leader of the vigilante gang with a specific hatred for paedophiles, was found guilty this month of the torture, imprisonment and murder of Mr Lyons. Later this year, he will face a pre-sentence hearing.
Two other members of the gang who took part in the ordeal, Jordan Bottom and Rikki Smith, were found not guilty last week of the killing of the father.

And I can't tell you how many times they just straight up confront the wrong person. Here's one example, and here's another, here's one more, and here's yet another.

These are not professionals. They are YouTubers looking for fame and relying on outrage and violence to get it, and they all-too-often don't care who gets hurt or killed in the process.