Because I‘m German and that‘s the way we use them in Germany. So my German mobile keyboard does this automatically, yes. Oftentimes I change it in English messages, sometimes it slips.
I'm also German and have never seen such weird quotes. Maybe this is some weird windows charset issue but definitely not widespread way of quoting text.
I don't know why, but in my browser, the closing quote is showed correctly (forward slanting) in the edit box, but backwards slanting when submitted. Weird.
