I'm willing to believe this, but want to take the space to beg people not to attempt to back into diagonal parking against the one-way flow of traffic.
One of our local parks intentionally has Back-In Angled Parking on its adjacent one-way street. Granted, it is in a residential, traffic-calmed area with speedbumps that is primarily for residents and park-users and not intended to be used to transit the area.
You still should, sometimes that means you have to go against the arrows. If the arrows are painted correct it is easy to back in,if not the lot owner should be considered at fault in any accident for incorrect directions