The exchange students arrive at eight and find the taquería closed. They conclude the reviews were wrong and go somewhere with a host stand. This is how you can tell how long someone has been here.
The stands on Avenida Álvaro Obregón do not open until the trompo is worth lighting, which is when there are enough people out to finish one. That is ten, sometimes later. Before then the neighborhood is doing something else. The cantinas are half full, someone is setting up, and the whole colonia has the feeling of a room being turned over between sittings.
What nobody explains to a semester program is that the schedule is not a quirk to be accommodated. It is the actual structure of the evening, and a curfew of eleven does not shorten your night out so much as delete it. The students who figure this out stop treating dinner as the thing you do before going out, and start treating it as the thing you do once you are already there.