I am not sure why but my son tends to have a hard time realizing what things are dangerous and what are not. He tends to think he's super human which tends to keep us on our toes. The thing I have learned with my son is many times trying to keep him safe isn't easy as telling him you can't do that you could get electricuted or you can't watch movie because it's bad.
We found that showing our son, for instance on movies, the warning/rating label that he quit hounding us about watching movies we deemed not age appropriate for him. He quit trying to get them from their high spots and was able to much easier identify which movies were okay and which were not. This also worked on other things too such as electrical cords, toys, shampoo, plastic bags and any other thing in your household that might have a label. We realized that words like 'warning' and 'caution' were so important for him to be able to recognize because of how these two words he tended to listen to.
Our house is much better simply because he has learned these 2 words as well as movie/game labels. It takes a lot of fighting and arguing because he realizes that it's not people being mean to him and telling him 'no' but it's the product telling him he needs to be safe or not to use it so he can stay safe.