List is special as a foldable because it is general. In 
other words, the function:

tolist :: Foldable t => t a -> [a]
tolist = foldr (:) []

is such that for any x :: t a where Foldable t, it is true that

foldr f v x = foldr f v (tolist x)

which is to say, any structure a foldable may have is preserved when 
transforming into list shape, as a foldable.