I was today years old

When I learned you’re apparently supposed to turn your car off when you’re putting in gas bc it’s dangerous or smth. I was just putting it in while my car was on and this guy went up to me and was like “sir you’re car is still on”, I lowk thought he was crazy but just turned my car off bc I didn’t feel like arguing with some old guy, but I asked my friends about it and apparently it’s “common sense” or some shit but like I never was told that before