Simple.
Backing in gives the driver control of their surroundings when operating a motor vehicle and parking it.
Leaving gives them a clear field of vision and control of their surroundings when exiting.
You’re a dumbass that you have not been able to figure this out on your own.
OSHA studies clearly show when the backing in method is employed accidents plummet.
Wow! I guess you're the smartest person in the world, except that smart people don't go around calling others 'dumbass.'