Is being this openly cruel and rude to others (see my example) a product of our culture?

Okay first of all, it's rude of you to point her out as "blonde, soroity-type". Knowing that information doesn't make anything more relevant to the story, and makes you seem stereotypical. And second, I laugh a lot when people trip and fall (that is, if they aren't hurt) - it's a different laughter than if someone was in distress like the test-taker in your story. Lastly, I do think it makes people think its okay to act that way in "real life". Many people find it a way to "get out their feelings" and be upfront and honest about everything. Some people do this harsher than others, it can be wrong at times, but yeah, I think our culture makes many people that way.