Because the government is EVIL. It is ruled by Satan, and his demons. No, not everyone in the government is evil, but most are. The government was meant to control the lives of the citizens of this nation. It's like a cult....it brainwashes people to get them to do what it wants. And so far it's working. People are so ignorant to the fact that as "the people" we could outnumber the government. But people are so afraid to stand up the government, that they do nothing about it, yet complain when they don't get what they want. To tell you the truth, this whole nation just sucks.
"Ignorance is bliss."
It's the same as you keeping secrets from people >because they have their personal reasons like you would yours<
There could be many reasons. My guess is to possibly protect the citizens from things that are advanced or complicated. In time many things are eventually filtered to the public. If you keep your eyes and ears open you can decipher what is going on behind those "secrets"...