Yes, and does anyone know if Girl Scout troops in other countries sell them, or is it a uniquely American thing?
Well, let's see... I've only ever come across the concept in American cultural imperialist media.
The wikipedia article on them states categorically "Girl Scout cookies are cookies sold by Girl Scouts of the USA (GSUSA)", so that sounds like they don't even do it in Canada (as that would be sure to get into the wiki article).
Articles on Girl Scouts / Guides generally don't mention cookies at all, though they're highly technical articles in either German and English and might not be expected to. The (English) article on GCUSA mentions them in passing in one sentence.
The "girl scout cookies" article also has versions only in English, Simple English and Bahasa Indonesia.
So yeah, on balance I'd say I'm reasonably certain this form of exploitation is American only. As yet.