I am a student here in the US.

I was certainly taught to hold and write with pens/pencils in the way that you describe. That being said, I have noticed that I and many of my peers somehow moved over to holding it with the thumb wrapped around the pen, and the pen held more straight up and down.

I am not quite sure what causes this, but I think that is is related to the way that you must hold many cheap ballpoint pens for them to write consistently. I personally fixed this bad habit when I switched over to fountain pens.