So this happened, and I still don't know what went through that lady's head.
I work in a stall in the middle of a hallway in a mall, so we have no gate and no external signs of being closed, but for the fact that all the lights are off, a sign that explicitly states we are closed and our opening hours, and that all the other stores around are obviously closed.
We open at 9 on Saturdays.
Now, when I got to my stall this morning it was around 8:35. Largely enough time for me to turn on the registers and do everything I needed to do for the stall to open at 9. A lady was sitting on the bench in front of the stall, tapping her foot. I didn't worry about her, since a lot of people sit there waiting for the bigger stores around us to open.
However, as soon as I entered my stall, she jumped up and came to me.
Lady: "Excuse me? Miss? You're late!"
I knew I wasn't, but I still looked at my watch. 8:35.
Lady: "No! You're late!"
Still half-asleep, I somehow wondered if she was right. I checked my watch again. 8:37. Ok, at least I knew I wasn't crazy.
Me: "I'm sorry ma'am, but as I told you we open at 9. I would be happy to help you then - "
Lady: "This is unacceptable! You are late and you won't even admit it?"
Me: "As you can see ma'am, it is only 8:37," I showed her my watch, but it did nothing to cool the fury of this righteous customer lady.
Lady: "But you're late! You have to be there when I arrive! You have to open right away when I arrive!"
I could only stare at her. It was way too early in the morning to explain basic rules of retail to a lady well in her fourties. She embarked upon the usual rant of 'this is horrible customer service! I'll never come back here!' Etc., etc., before finally leaving.
At 3:31 pm, and she came back to the stall.
No, she did not actually buy whatever it was she wanted to buy this morning. She only wanted to tell me how much of a terrible person I am, and how I shouldn't be 'allowed to work'.
I can't say I expected much more.