Linguistic profiling and discrimination

I took the linguistic profiling test and was kind of surprised by the results. Their classifications of race contrast with anthropological ones, so it was more that they were asking for ethnicity which can include various races. I noticed also that there could be a cultural influence to this test, that if calibrated to other cultures they might even be able to identify easier. E.g. tonal language acquisition also may have a genetic basis, so speakers of a tonal language like Chinese, or Vietnamese could maybe more easily pick up on many foreigners. More about this can be read here: http://www.sciam.com/article.cfm?articleID=D87BB853-E7F2-99DF-3CE5ED42E188F867

I think the anti-linguistic discrimination video did present one view of what does and can happen, but it came across to me as too one-sided. The frustration that can come with misunderstanding occurs much more commonly from my experience than attempting to make someone look like less worth like in the video. Here's an example of what I mean:

http://www.youtube.com/watch?v=Cu-hW75wF4E

But I just thought that this is not only between languages, but also within them, like in speech disabilities (i.e. muteness or stuttering).

I can understand where the responses for equal treatment came from, they themselves feel an injustice has been done to them. They're going to look out for their best interests.

Why we discriminate on dialect? I'm not sure. But I think that languages and speech in humans itself accommodates the pack mentality, there is maybe a desire to act protectively.