Divide and Conquer?

  I was scrolling through my feed and I came across this post and I think that it deserves some attention. What this post is doing is pointing out that every group of people have those within' its ranks that poorly represent the group as a whole. In the images here wee see those stereotypes of violence associated with 4 groups of people: Mexican, Middle Eastern, black, and white. The problem is not with the line "How some ______ (people) are." The problem is with, "How society sees ______ (people)." Look at the second image in each pair. The only set where the second image is different than the first is the one regarding white people. Why is this, "How society sees white people?"
Before we start pointing fingers and screaming "racist" let's focus on why it is that society sees everyone as the second image in each pair. We all KNOW, regardless of what you say or post, in person or on social networking sites, you KNOW in your heart that not all of a people represent the stereotypes attached to them. There are some people in one group that may not know a single person in another group. So why does "society" see certain groups of people a certain way? Could it be that many of the sources from which we receive our information portray them that way? I didn't grow up around Mexicans and very, very few Middle Easterners (I don't like the way the term "Arab" sounds).
I grew up around black and white people so I know that the first image in the pair regarding those two groups are correct. I had the fortune of serving with, working with, and meeting Mexicans and Middle Easterners, along with many others once I went out into the world, so I know now that the first images in those sets are correct as well. I have also been to Mexico, have lived in areas with a where there have been a large number of Hispanics, and have been to the Middle East. In all cases involving ALL peoples I have seen both the good and the bad. I happen to be in the Middle East (Iraq) during a time of war, yet met some of the NICEST people I have ever crossed paths with in my entire life.
What I'm getting at is that the way a society views people is based on the information they receive, and a lot of that information comes second-hand from individuals with an agenda. Again, look at the second image in each set. What is the message that you are being fed by this? What do "they" want you to think of these people?