Seriously though I don't understand how people are so against stuff being tagged.
Like someone comes up to you and says
"I'm sorry but my brain has decided to be shitty and cause irrational fear at the sight of squirrels/makes me super uncomfortable thinking about them. Can you tag them so I can avoid seeing squirrels?"
From where I stand there are two things I could say to that if someone said that in my askbox. (Depending on the situation)
1) Sure, no problem, I hope you're okay now and will do my best to tag it all in the future.
2) I'm sorry, but my blog is like 99% squirrel pictures, even if I tried tagging them all I'd probably miss one, and honestly the 1% of content that isn't squirrel pictures probably isn't worth it for you to keep following with that risk.
I can't imagine ranting about how squirrels are not a trigger, because I don't know this person's life or their trauma, and I definitely don't have the information needed to tell how bad it actually is.
Like a trigger can be anything, and even if it's just a squick or they just don't want to see it then why not tag that, instead of rolling the dice with someone's mental well-being just so you can post the occasional squirrel picture without tagging.