First, we need to clarify the definition of "rusty". Rust usually refers to the process in which metal reacts with oxygen and water in a humid environment to produce metal oxides. This phenomenon is most common in iron and iron alloys, and the resulting iron oxides appear reddish-brown, hence the name "rust."
Next, let’s look at the metal aluminum. Aluminum is an active metal that quickly forms a dense aluminum oxide film upon contact with oxygen. This film can tightly cover the surface of the aluminum, effectively isolating the aluminum from further contact with oxygen and water, thus protecting the aluminum inside.
Unlike iron, aluminum's oxide (aluminum oxide) is white, and because of its density, it does not continue to erode the metal as deeply as rust does, but rather protects it.
Therefore, although the appearance of aluminum beverage cans may change due to various physical and chemical factors during long-term use, it will not "rust" like iron.