Office Pranks, Office Humor, and Office Stories - One Crazy Office

This is one thing I will never understand in the business atmosphere. We are all supposed to be working towards the same goal and yet some people know more than others about what is going on ALL the time. Some things are worse than others, but there's one profession that it is pretty important to pass things down and make sure everyone is on the same page. Security in a corporate environment. You may not think so, but think about this.
Let's say someone gets fired and it was a bad firing and the guy says he is going to come back and make everyone sorry. Odds are they are not going to come back, because the people you really have to worry about is the people who don't say anything and just walk out. Well this happens a lot where I used to work. What makes it even worse in some areas if your security isn't a employee of the company they are providing security for, which is most every place of business. But you will not want to tell the guards everything because they are not apart of your company so a lot of people don't think they are a real part of the team anyways.
Now other professions need to know information is used as a tool of power over your other coworkers. They think they are so much better just because they know something that you don't so they have the advantage of doing a better job than you in the first place. What would happen if no one would stab each other in the back? That everyone would work together to accomplish whatever it was in front of them. There would be a lot less wasted time and therefore less money thrown away over petty rivalries. I know of course the answer though is greed.
And there is so many other things that could be said about this topic, but I would like to know what everyone else thinks and let them talk about what they think about the need to know basis. What is everything was out in the open so no lies could be told behind the scenes, so they could just use the term well it was on a need to know basis?