Whatever they are, they're programmed like every other animal with instincts.
I've seen deer do some truly stupid things, but in the woods, they know without thought when something moves. The eyes trigger the neurons to fire straight to the muscles without going through the wrinkly stuff at all. You do the same thing with snakes and spiders. It takes training to not immediately jump when surprised.
I've always assumed they exist in small enough numbers, and we just aren't putting that many cameras out, and they don't have to see a camera to sense it. I've always assumed they simply freeze, study the situation, and divert around if they see, smell, hear anything unusual. I can hear a trail camera click, I can see the red illuminator, and my hearing is wrecked from decades of drumming and driving loud cars without hearing protection... But I can head the clicks. My vision is terrible, astigmatism, floaters, somewhat color blind but I can see the red lights.
And if there's only a few hundred of these things, a million cameras in the woods aren't going to see one.