Is this a cultural thing?

I was always taught there are 12 notes, while any standard scale contains only 7 of them. (The chromatic scale obviously being the exception which contains all 12.)

Accidentals are just for notation -- obviously B-flat and A-sharp are the same "note", just as F-sharp-sharp and G are.

Our entire turning of equal temperament is based on 12 equal intervals, not 7. So I'd argue parent commenter is correct -- notes are base 12, not base 7.