Actually, I think your WordPress example doesn't support your argument very well. Yes, the two buttons are far enough away from each other that you probably wouldn't accidentally click one when you meant to click the other, but the "Move to Trash" link is only slightly smaller than the "Update" button, and more importantly, the "Move to Trash" link is near the left screen edge so is probably easier to click than the "Update" button (according to Fitt's Law).

Jeff, Over the years I've used quizzes, on-site programming questions and take-home programming problems as part of of the interview and screening process. I'm always amazed at how much you learn by asking someone to write some code. I'm also amazed at how frequently people bomb these fairly easy problems. Sometimes I even have candidates that refuse to do the programming problem! It's like they feel offended that I'm asking them to demonstrate the very skill I'm considering hiring them for. The nerve of me! While I think I've gotten better at screening and interviewing over the years, I think the best approach I've found is to hire people on a contingent basis for 3 months (consulting contract) with the understanding if both parties are satisfied about the arrangement after that time, then they will be converted to full-time.