The generalization that crosswalk buttons are not hooked up makes me wonder if David McRaney is not as smart as he thinks he is.
I've heard that the "close door" buttons to elevators do nothing as well, according to, "somebody told me that." But I've been in many elevators where they sure seem to work: doors start to close immediately after pressing the button, when there would otherwise be a delay after the last beam-break event.
Behaviors of these systems are not entirely driven by these buttons: they're just inputs to a larger system that may at different times not consider them.
I would love to hear comments from people with first-hand experience: traffic control equipment technicians, please chime in!