Do you notice how we negotiate paths when we are walking? body language, with particular emphasis on the position of the head and eyes. Try this experiment: as you walk towards someone without a clear path to their left or right - walk with intent to go slightly one side with your eyes/head slightly to the other, usually your intent comes across far more ambiguous and requires more negotiation than usual... now imagine people are not looking where they are going (literally), while appearing to be looking where they are going. And I don't buy that AR magically solves concentration by keeping your field of view.
At least with those zombies staring down it's clear they are distracted so you can ignore their body language.