Because there are a fair number of idiots out there. You're always going to have them. They can even become doctors, lawyers--and inventors of supposedly foolproof firearm safety devices, for that matter.
Your proposed solution does not address idiocy effectively--because it requires a perfect state of situational awareness on the part of the legitimate user in order to work properly, and such conditions are not the norm under the circumstances where one needs a firearm immediately.
I never said anything was foolproff you did. Lets stick to the facts if you want to make up fairtales start writing kids books. This is not an everthing for everyone invention no one has ever said that.
I guess if you can't find fault make stuff up to find fault about.
Ok Einstein show me your great idea.
Mike Worley Inventor of the Safety Bullet