National pride? One could just frame this as American students teenagers being more independent-minded… and more rebellious (the last part can be both a compliment and not).
If you look at the opposite of rebellious as conformist both have negative connotations, and I think in general American culture values at least in theory rebelliousness over conformity, even if in practice there is a strong conformist push from those in charge.
Looking from outside the US and basing my opinion on news, movies and comments in forums like these, I see there is an enormous conformist push from all levels of society (school, work, religion, military, gangs, culture, politics), much more so than in most other western countries.
Granted, that could be just my impression due to prevalence of US culture on the internet and in every day life, and all countries (western and other) might have similar levels of conformist push but it is the US that prides itself on individualism so the level of conformity just stands out more.
Do you think traveling to the US to get direct personal experience, unfiltered by the media and internet, might give you a different perspective?
What makes the US seem so much more conformist to you than other western countries? I didn't think it was more conformist than countries like Spain, France, Germany, etc.