As a hypothetical situation, let's assume I'm throwing a party at my house where the theme will be fruit juice tasting.  Each person will bring a different flavor or style of fruit juice, and then we'll all drink 'em up and vote for the best one.  The entire night hinges on the fact that each person must bring a different flavor, otherwise we'll all be stuck drinking store brand apple juice because it's the cheapest and easiest to find, and as such, the invitations specifically ask each person to reply with which fruit juice they'll be bringing.  Lo and behold, about one-third of the people follow these directions, with the remaining people either bringing duplicates or calling me from the store right before the party to see if their choice is ok.  Cursed be ye who fail to follow my directions. 

This reminds me of another direction following failure that occurs on a fairly regular basis.  I manage a group email list and occasionally send out an opt-in email, i.e. I ask people to respond if they want to continue receiving my emails, that way the people who would like to opt-out don't have to do anything.  Without fail, I'll see group members in person later who will verbally tell me they'd like to remain on the list.  I'll ask them why they didn't just respond to the email, since they had already received it and gone through the trouble of reading it and comprehending what it said.  They'll say it was easier to tell me in person.  Part of me dies each time this happens. #sociology