Actually, I think you misunderstand the analogy. The color of the middle wire on the distributor is something you'd like a prospective mechanic to know, so he isn't learning on your time. It isn't, however, something that is in any way relevant to driving a car. I think this is why your comment provoked such hostile responses.

The programmer equivalent of the middle wire color question is something like, "Is the 3-phase power supply on XYZ mainframe wired in a delta or wye configuration? As a followup, what is the input frequency tolerance?" A sysadmin might need to know that, and an electrician certainly would, but it is far, far outside the purview of a programmer. [Edit: I'm assuming the programmer to be someone writing software running on the mainframe, not the firmware for a microcontroller in the power supply]

Maybe you're just a very good interviewer and haven't had to deal with the 90% that are crap? :+)