IMO there isn't a good answer to this. A deer isn't a deer, isn't a deer, isn't a deer.
People like to argue that it doesn't bother them, but just because you saw some that didn't run away, that doesn't mean there weren't others that did (and you just didn't see it).
People say "they're used to it." Yeah some of them can get used to it. I used to work at a large public shooting range. At times the deer would feed just feet in front of the benches, 30 yards away from guy shooting rifles. Does that mean that's what deer do? I've also shot at a dozen other ranges where I didn't see that.
While bow hunting, I've seen evidence that it does scare them (or can), having them literally right pas me, feet away, from a neighbor shooting.