The phrase "Like a deer in the headlights" suggests a person who is so startled and afraid that they cannot respond to a threatening situation.
However, looking at this deer oh so carefully holding herself still as soon as she saw us, with only her eyes moving, tracking us; it makes me wonder.
Might it be that deer have survived by holding themselves still? By making themselves hard to spot, and thus evading the eyes and teeth of predators?
If so, then might it also be that the deer may not actually be frozen
with fear, but rather just practicing a strategy that in nature is
exactly the right thing to do when faced with a threat. But which just so happens to be exactly the wrong thing when the threat is not a wolf, but an on-coming car or train?
If these speculations are on the mark, then the phrase "like a deer in the headlights" should really mean: Someone who is taking a strategy excellently suited for one situation, and using it in a different situation where it is exactly the wrong thing to do.
[This is a guest post. My daughter and I saw a deer on our walk yesterday. The deer was moving until she saw us. M suggested a blog post on the 'deer in the headlights' idiom. I suggested a guest post. The picture is the deer we saw.]