I do not want to come off as being ignorant or uncaring but... this is how the world works. Nobody in the history of mankind, or even in fiction, has been able to completely stop injustice, ignorance, and prejudice. Moreover, any attempts at stopping injustice get mangled in politics. Is abortion injustice? Does war ultimately serve a greater good? Does affirmative action help create equality?
We do not live in a fair world, and even people who try to make it a fair world have to push and shove to have their opinions heard on a planet of 7 billion people. However, it doesn't mean you can't make the world "suck" less. If you really want to stop injustice and unfairness, there are several things you can do to help. First and foremost, become educated. I mean become educated in general politics. Get a worldview. Do not listen to just CNN or just Fox news. Try not to associate yourself with just one political faction and pretend all the other parties are neanderthals (as many people sadly do). Listen to what the Conservatives have to say, listen to what the Liberals have to say. Moreover, if you want to help make the world suck less, be good to other people. Treat other people politely. Volunteer your time to help other people, maybe in a soup kitchen, or a community event. You wont change the world, but you will change many people's lives.
If you sit around waiting for somebody to solve all of the world's problems then you will be powerless and they will go unsolved. If you take initiative and start trying to make the world a better place, then it will start to become one.