This is not a public McDonald's restaurant after all. Although it sure does look like one. Let me give you some intel from one of my secret agents. It will still be creepy and mysterious because it is rare to see someone there, but it might explain a few things:
This McDonald's is in an industrial area in, naturally, the City of Industry in California. It is production area that is a fully working McDonald's, but not for the public. As you can see, it is gated so if you drive by, do not go in expecting to eat there. Stay on the street. Again, private property, drive by slowly and use your eyes.
If a movie needs a scene from a McDonald's it could be filmed here and their commercials are filmed here as well. The products used to make McDonald's food are made in the City of Industry. So, this is why this is here. Right next door over they have this:
It is a training facility. Okay, so there you have it, I am sure there are more secrets that go on behind these gates, but we are not to know. That is the way of the greatest dominating worldwide fast food franchise. So, eat your cheeseburger with pride!