Aluminium requires a great deal of electricity to refine. It is very economical to recycle aluminium.

The same cannot be said of most other recycled products. Many actually cost more to recycle and consume more energy and create more pollution than making it from scratch but it makes the tree-huggers feel better so they push to pass laws to require it, even if it is a dumb idea.
Much of our "green" movement is based on irrational emotion and nearly void of common sense or logic.