"We both got A's" ? Seriously?

The last line in the movie was: "We both got A's", referring to the grades they got at their final exam at summer school.

Now, I can understand people with English as their 2nd language [ or even their main language for that matter ... since we`re not all perfect ] not getting the fact that " 's" isn`t how the plural is formed, but seriously ... A MOVIE? How many people work on a movie? 10? 100? 1000? More? And neither of them knew that to point it out in the script, the final cut, director cut, edits, filming and all the stages a movie goes through before it`s being shipped out to the masses?

I get mad when people make crass generalizations and consider Americans, as a whole, a bunch of uneducated idiots, since every nation has its bad apples [ which is true! ], but come *beep* on! GET *beep* RIGHT IN YOUR OWN *beep* MAIN LANGUAGE GOD DAMN IT! Seriously ............................