Me too, and that's why I set up our hiring process such that candidates are welcomed to supply code samples via github and other means if they can. However we recognize that this simply isn't feasible for everyone, and it's not held against anyone if that's how it is.

For me personally, nearly all of the work I've done over the last handful of years is on github, however most of that is contained in private repos that I can't share. I don't think that's what people mean when they say that I'm supposed to have everything on github :)