Contrary to some opinions, there are actually four possible reactions to injustice: ridicule, apathy, sympathy, and action. Ridicule isn't nearly as common as its passive cousin, apathy. And action isn't nearly as common as its own passive equivalent, sympathy. Lots of people are either apathetic or sympathetic when they're told, "Something else is wrong with the world." But the problem is that, by the time the average Westerner (there's no reason to restrict this to America, is there?) is an adult, they've been exposed to so many injustices throughout the world that they can only spare the time or energy for those two reactions.
Action is the most admirable response, of course. But it's also crippled by reality. Usually, there's very little a given person can do to combat a given injustice. And if they can, they may not have the time or resources to do anything.
An example: homelessness is unjust. I personally think that homelessness should be eliminated, actively, by every person in society. But there's only so much I can do to change everyone's mind about this. So I do what I can -- but again, there's only so much I can do. I have a family to support. I have a job to attend to. I have to sleep a certain number of hours every night. So when the opportunity presents itself, I do what I can to combat this particular injustice, and then feel guilty that I can't do more.
But of course, this is only one injustice, and there's any number of other ones to attend to. People imprisoned around the world for their beliefs. Animal species being driven to extinction by human expansion. Prisoners failing to be reformed before release. The environment changing for the worse. The inequality of the social classes. Corrupt governments. Starving children. War. Sickness. Death.
The list goes on and on, of course, because this is a fallen world with injustice everywhere we look. And by and large, there's nothing I can do about most of it. The most I can realistically expect to do is be a good example to others and solve what problems I can, when I can, with what I can.
And every once in a while, I get another twinge of guilt because I imagine I'm not doing enough. But I can't solve every problem there is. I have to turn away from most of them, and hope and pray that someone else in a different position than myself can do something about it instead.
This isn't being cold or callous. It's not the same as saying "Fuck it." It's recognition of my own mortality.
I'm just an American. I'm not God.