Michael J. answered 03/06/16
Tutor
5
(5)
Effective High School STEM Tutor & CUNY Math Peer Leader
The target audience are groups of people that are being affected by the stereotypes. Black people are the audience when discussing sports skills, Canadians are the audience when discussing politeness, and blondes are the audience when discussing lack of intelligence.
To answer why they are the targeting audience, you will have to take all of experience with such groups. Perhaps things you have observed in person, by listening to other people's conversations, and what you have seen or heard so far on TV/media.