It's the exact same parking slot no matter which way you're driving in/out.
I disagree that it overall takes any more time no matter which way you park but one thing is for sure and it's that backing in is safer. It's way more common for people to get hit by a car that's backing out of parking slot that by one backing in. You can't see your surroundings when backing out because of the cars on your both sides but I can see the entire parking slot when I'm backing in.
It's faster to drive forward into a parking spot than to back into one. It's also faster to back out of a parking spot to back into one. Therefore, it's never faster to back into a parking spot.
You're clearly married to your opinions so I don't expect you to change your mind but perhaps consider the possibility that someone whose been backing into parking slots daily for over 15 years perhaps doesn't lack that skill. Turns out that practicing makes you better at something. Who would've though.
You're blocking people the exact same way when you're backing out of a parking slot. I can't believe how this can be so hard concept for you to grasp. Cognitive dissonance at its best.