This person does not complain about not being served ten minutes after the establishment having closed, but about the fact that not one of the four employees could be arsed to let the guest know that they're closed.
Honestly, and I'm not saying that this is a universal, most stores do have a sign with their hours of operation on or near the door.
And if you go to a store and can't open the door, the fact that the store is closed really should be the default assumption.
I've tried the door on closed restaurants before and had someone open it and explain that the place is closed, but I've also had people just expect one to read the sign. I don't think that just because there's someone in the establishment, that they should be obliged to spell the thing out and give you the hours. It's nice if it happens, but...
Never unlock the door after close, she probably fits in the typical category of inconsiderate assholes who "just want an X," but this is also a common robbery technique. They'll have someone nonthreatening knock on the door to try and get you to open it to say "fuck off we're closed" and the second you do 4 dudes with guns (or knives, machetes, whatever) run around the corner and rush the door.
Just hit em with the "we're closed" lipsync and the "we're closed" international symbol: hand chop moving away from the body in front of the dominant hand side of your neck 2x.