Few notable experiences are expected at any basic fast food restaurant, but one certainly doesn't anticipate one which has you questioning the fate of the human race. When you ask a person standing behind a register if they are open and taking orders, you typically expect a response of some kind. Simply saying "yes" or "no" would constitute a classic, if not bare bones response. Tack on "sir" to that and you have all the elements of perfectly genuine and normal human interaction. But to not respond at all, nor show any visual acknowledgement that I, a real person, am standing directly in front of you and have verbalized a question makes me ponder larger societal questions that I had not anticipated thinking about when I set out on my quest for my egg mcmuffin.
The crowds of unserved people around me confirmed that this interaction was indicative of larger issues, and a poorly managed restaurant generally. Do yourself a favor and head across the street to Chick Fil A.