In Japan, everybody backs in, all the time, no matter what, and they can typically complete the entire process faster than I can shift into reverse. It’s been joked that a car parked nose-in in Japan is always owned by an American.
I’m not sure what the rule is at this base, but at my previous base, the rule was never to park government vehicles back-in. Presumably this is to avoid accidents from people bumping into other parked cars, although it is also worth mentioning that we are required to use a spotter whenever backing up a government-owned vehicle, so you’d think that’d making backing in even easier for us.
I usually don’t back in unless I think of it and have some time to kill before getting out of the car. When I back out, I do so very slowly and try to take advantage of the tendency for most modern automobiles to have transparent windows, allowing me to see through other parked cars. Granted, this only works when I’m parked next to a vehicle that’s not significantly taller than mine.
I haven’t had a lot of experience with the sort of people who insist on continuing past within inches of a reversing vehicle, but I’m sure they’re out there along with the folks who become enraged at people who signal them by flashing their high beams and people who drive on highways at the posted speed limit.