I can't really code myself out of a paper bag either with a stranger watching and questioning me while I'm doing it. I just get so nervous and can barely think straight (in general I get rather nervous being watched). One time they asked me to do a function I literally exactly have on my public GitHub as part of a project (remove duplicate entries from an array without sorting; it's just a few lines and pretty straight-forward) and I couldn't really do it in the interview setting.
Of course I wasn't present in your interviews and I'm not saying some of those people really couldn't code at all. I've worked (well, "worked") with some of them so I know they exist. But I'm not so sure all of those who flunked couldn't code at all. In my experience I'm not a hugely unique individual.
If you don't want to accommodate that then fair enough; it's your interview process. But just saying your perspective is perhaps not entirely correct.
Of course I wasn't present in your interviews and I'm not saying some of those people really couldn't code at all. I've worked (well, "worked") with some of them so I know they exist. But I'm not so sure all of those who flunked couldn't code at all. In my experience I'm not a hugely unique individual.
If you don't want to accommodate that then fair enough; it's your interview process. But just saying your perspective is perhaps not entirely correct.