I go to my local post office nearly every day to drop off packages for online purchases. A couple of years ago, I had a van full and it would have taken many trips to bring them inside. I asked a clerk if there was an easier way. The supervisor came out and told me to drive around back. I came around back to the fenced (not gated) employee area. No one met me. So, I walked in. He pointed me to the empty carts. I took one, filled it up and brought it back inside and asked him where to put the cart. I handed him my paperwork and left.
This was much easier for me. So, I started doing it every trip (4-6 times per week). The postal clerks all know me, see me and interact with me in the back room. I go to the far corner where the supervisor has his desk to hand him the paperwork. It seems like a decent arrangement. Makes it easier for me. No lines. And easier for them as I move the packages right to their sorting area.
Although it is clear to me that I am allowed there, I still feel a bit odd for being in the clearly labeled "employees only" area. I would think that at any time, they could revoke this permission, but do not since it is mutually beneficial.
I had some "Facebook lawyers" tell me that one day, I will get arrested. While I guess that could happen, I find it far more likely that if a postal police officer happened to be there one day, he'd question me, question the supervisor and either tell me that I cannot (or can) continue to access this area.
Does the long-standing policy of allowing my access grant me some-sort of (revocable) license to continue until told otherwise?