Personally, I find your approach appallingly rude, aggressive and confrontational. I would hope that I would never do the things you listed in the first place, but if I had, say, kept my backpack on without thinking, I would be distinctly unimpressed by a prod and "take it off NOW". In fact, nothing would be more likely to make me not take it off.

If someone is bothering you to the extent that you have to behave like this, then I would politely suggest that, whatever their shortcomings, it is in fact you who needs to remove yourself from the situation.