Aluminum isn’t transparent and can’t handle certain chemicals, but it’s not that expensive—if it’s recycled consistently. It’s routinely replaced by steel for,

Aluminum isn’t transparent and can’t handle certain chemicals, but it’s not that expensive—if it’s recycled consistently. It’s routinely replaced by steel for, say, cans because that ends up being cheaper (with thinner walls), but steel is also cheaply and effectively recycled. It also often has a thin plastic layer when holding acids (like Coca-Cola), so it’s not a complete replacement.