I think it got started because photographers were repeatedly getting harassed by the police/Security in the early 2000s with spurious terrorism act claims.
Then it got co opted by the conspiracists and the freemen of the land types.
Photography is so ubiquitous these days that these "auditors " often have to be more and more provocative to get police interference.
That's it. Following incidents that impacted journalists and photographers, many police forces issued clear guidance to officers to allow people to take photos unhindered, but press associations also accepted there might still be a need for the police to clarify why someone is where they are - as well as be asked move if it might impact a police investigation (another thing auditors love to do - get in between the police and who they're talking to, sometimes putting themselves in danger).
I would say that things improved a lot, but now these idiots are not just taking photos as that would likely be ignored. They have to dress and act suspiciously so as to attract attention, and actually put themselves in harms way at times - potentially both themselves and the police in danger.
Sure the police have questions to answer for how they treat people at protests and the like, but the police are less likely to be tolerant when some people are goading them.
But if they can make money then technically these people do have jobs. I don't think YouTube should be allowing profit from such content, and without a profit element I bet 99% of them would suddenly give up on their crusade and do something else.