[lostmsu]

This makes no sense. In either case the car traverses the same space once forwards and once backwards.

[pegasus]

That's true, but what GP is saying is that when you're pulling out, you are traversing the part of the space overwhelmingly more likely to contain passing pedestrians and vehicles with full visibility.

And then some parking spots require parallel parking which is best done via backing up anyway.

[lostmsu]

I don't think you understood what my comment says. The whole point is that it covers your "but".