

Your eyes adjust to the available light to a radical degree. If you are in a room with 5 lights bulbs and turn all but one off, it will probably only feel 25%-50% darker.
I was trying to make my bedroom as dark as possible so I could sleep in. I turn off the lights, it felt dark for like 2 seconds until my eyes adjusted. Then there was all this light coming in around my curtains, it felt just as bright as before. So I tapped those to the wall. Man it was nice and dark for a few more seconds then my eyes adjusted and there was all this light coming in from under the doors. So I put a towel in front of that. Then it was dark, but I could still see a little because it turns out my curtain tapping was not great AND there was light coming in around the doors. My point being, if you are young and healthy your eyes can be really good at adjusting to low light conditions without you even noticing.
Because you don’t see the cars going the same speed as you. If everyone on the interstate was going 60 you would only ever see the 10 cars near you. But 10 people going 70 could pass 100 cars. Each of those drivers would see 10 cars going 60 and 10 cars going 70. Despite the fact that less than 10% of the cars were speeding.