Burning plastic/paper/other packaging gets you a lot of toxic stuff in the atmosphere. I know there are filters and processes and whatnot, but it just feels wrong and smelly.
Aluminium recycling actually works great, recycled aluminium is 95% less energy expensive and some 75% of aluminium comes from recycling. (1)
Steel could also be recycled like that, I guess ships are a lot more difficult to cut apart and melt down than cars, because they are heavier and larger (citation needed). At any rate, we put a lot of resources and energy into the steel for cars, maybe we should use that steel as much as possible instead of putting more energy into more steel.