I think you mean why not some people try to change the society?
What is society? When we live to gather it is called society. This means we should learn how to live together?
It is the duty of each of us to learn & right of each of us to be taught.
So we start it with our own personality. That I should do certain things & will not do certain things which are harmful for the society.
Then we tell it to our friends & relatives. If some body is doing wrong we should have a system to check it.
Other people can learn when they look at you that you are what a great human being.