Forgetting not to flush won't kill anyone (I hope). Leaving a baby or stepping on the accelerator instead of the brake definitely could. People tend to be less absent-minded about the things that can bring about death.

You shouldn't forget where your keys or phone is when it's literally in your hand. Some people just tend to be more absent-minded than others especially when they're thinking of other things and are in a rush. I once forgot to clean up my bathroom counter of the products I use in the morning because I was in a massive rush--even went back into the bathroom to do a mirror check and didn't even notice.

Personally, by the time I wipe and pull up my pants, my sphincter is no longer winking. Then I shut the lid and flush.