As a non-citizen residing in the US, I find this phenomenon particularly noticeable. Like when Dzhokar Tsarnaev was arrested for the Boston bombing and the question of whether he should have his Miranda rights read to him was discussed in the media, the argument seemed to generally hinge on 'but he's a US citizen', as if, if he weren't, obviously this conversation wouldn't be worth having; or when the nature of US drone strikes comes up, and people express specific outrage that drone strikes have been used to assassinate "US Citizens abroad", as if that somehow changes things.