Simple Requests- Not enough anymore

Have any of you noticed how simply requesting that someone do something is not enough to get them to do it. Now people, and high school students(non-people ha ha) need incentives and consequences to follow the rules. Case in point: Our students are not allowed to wear hoods in the building. They know this, but everyday we say, "Remove your hood, please." about a million times. They look at us like we are stupid and keep the hood on. Of course we are between classes and can't chase them and give them a consequence, so they don't do what we say. Or, even better, they do it when we ask. Then, when they turn the corner the hood goes back on.
The problem is not limited to the students either. The principal has started "cracking down" on teacher dress code. I know you would think they wouldn't need to be told. Anyway, a specific request was made that on Friday which is spirit day AKA jeans day teachers need to be sure and wear a school shirt, or shirt celebrating upcoming holidays. I admit I had been wearing any shirt I wanted before the "crack down". I didn't think the high school was as strict as the intermediate I worked at before. Now, because I respect authority, I am complying with the rule. As you would expect there are a few people who are not. I was shocked to see professional people not following the rules. I thought to myself, maybe they just forgot this first time. Then, two more Fridays passed with the same result. The principal says she is not going to police us like children, so some people take that to mean I can do what I want.
I know some of you are asking, do you always follow every rule? The answer is no, but I do follow most of them. I speed, I may take 21 items to the 20 item express lane, but usually I will do hat I am suppose to do. I may sound like a hypocrite, but I think many of you can agree with me. I just wish people would do the right thing, not just the right thing for them. Sometimes there is a difference.