The English Language needs the Polite form of "you"

As a kid in school, learning French and German, that words like "ihr" and "vous" were the polite forms of "you".

Problem was, as a early teenager, I couldn't understand what was impolite about regular "you".

As I've got older, I've come to recognize the failings of English in this regard. Oftentimes, I'm in a situation where it just seems too familiar to call somebody "you".

I was on the train at Denver Airport last week, and an automated voice said something like "Please stand clear of the door, YOU are delaying the departure of this train". That seemed really offensive to me.

After writing this, I found this very detailed Wikipedia article on T-V Forms. Who knew that Thou/Thee were the familiar/singular forms of you in English, and ye/you were the polite/plural?