I just noticed your username is Hungarian for sure. Pun intended. :) If you've spoken to a lot of Hungarians, as I have, I think some of the distance between "school English" and "street English" for Hungarians has to do with the distance between English and Hungarian. I haven't noticed any school/street difference with Germans speaking English. Most of the Germans I've met I could swear speak English as a first language. For what it's worth, I speak intermediate "school Hungarian", but "street Hungarian" still feels a lifetime away for me. When I learned Spanish I feel like I went from "school Spanish" to "street Spanish" in 3-5 months.