I dont like doing it either, but in my case the reasons arent quite the same.
I have the usual autistic tendancy to never look directly at someone when talking to them (with a couple of extremely specific exceptions, and even then only if I'm in a good mood). But also there's, uh... "gender issues", to put it bluntly. Anyone that's had to deal with that type of crap probably understands the avoidance of mirrors in relation to it. The more it's bothering me, the less I can tolerate the horrid things. Lately I cant deal with them whatsoever.
It's the same with photos, really. There is a bit of an added element to that one though: Even if I didnt have problems with, uh, that stuff... I honestly dont like photos of people in a general sense, and that includes myself. Just... feh. I'm not interested. And so many such photos look so... forced. I'd rather see photos of animals and landscapes.
Also the experience of having a photo taken is just beyond my non-existent patience. THe only people that would see a need to take a photo of me are relatives, all of whom are older than I am. In other words: They dont deal with "tech" very well. They do spend half the bloody day attached to their stupid phones (facebook and whatnot) but ask them to do any other function and it's like trying to get a concussed chicken to perform advanced calculus. Eventually, I will always snap at them. "JUST TAKE THE BLOODY PHOTO ALREADY". Lately though I just refuse to stand for it. If at the very rare sort of family events I'll actually go to, I can tell when "bloody stupid photo time" is coming and will leave without anyone noticing. I'd get far enough away via car that by the time anyone did notice, it was "oops, too late to come back, sorry".
Granted that might be a bit harder now since I got a different vehicle recently. It was easy for people to not notice the absence of my previous small car and thus not react to it quickly. It's another matter when it's a van the size of Kansas.
The worst bit of photos now though is that whoever took the horrid thing will insist on showing it to me for some... baffling reason. Like "Here's you in this photo ISNT THAT SO GREAT". It's the mirror thing all over again. Just... ugh. I hate the whole thing. Photograph the dog instead, please. Attention certainly pleases him, it's a win-win.
But yeah, them's my reasons. Negative, I know. But then I usually am.