> So it's a simple concept that takes no time to learn, and they haven't yet learned it before showing up for an interview. Doesn't that tell me something right there?

It tells you that it's trivia. There is a world of trivia surrounding any topic, and 100% of the time you will be able to nail somebody on not knowing something that's simple to learn if you just pick the right piece of trivia.

> Should I expect them to be knowledgeable of complicated concepts if they are not knowledgeable of simple concepts?

OK, so Cocoa has this OO IPC technology called Distributed Objects. It's really brain-dead simple (like four lines of code to set up), but it's pretty archaic. I have more than a decade of experience in Objective-C/Cocoa at this point and feel pretty confident saying I have a solid understanding of the language and framework — but if you asked me to write some code using Distributed Objects, I would have to go look it up. I'd have it down in a couple of minutes once I knew it was needed, but I could not produce it on the spot because you can't hold every piece of trivia in your mind all the time, and this particular bit of trivia has never been needed for the things I've done.