How is the Foldable instance of (,) useful?

I mistakenly applied length to a (pa,ir) and took a little while to find out, because the code would compile!

So I looked up :t length, which told me that its argument is only required to be a Foldable.

That's how I found that there's a Foldable instance for (,):

instance Foldable ((,) a) where
    foldMap f (_, y) = f y

    foldr f z (_, y) = f y z
    length _  = 1
    null _ = False

which incidentally overrides what would be the automatic definition of length.

What is a Foldable instance for (,) useful for? Especially considering that some of what derives from a minimal definition (null and length) of it has been overridden anyway.

Related question.

One way through which something nontrivial can be done with Foldable ((,) a) is bringing in the Foldable instance for Compose:

ghci> import Data.Functor.Compose
ghci> sum $ Compose [("apple", 1), ("banana", 2), ("orange", 3)]
6

Also, Foldable happens to be a superclass of Traversable, which in turn grants us sequenceA:

ghci> sequenceA ("strawberry", [4, 5, 6])
[("strawberry",4),("strawberry",5),("strawberry",6)]

The perspective these instances suggest is that of (a, b) values seen as b values annotated with an a tag. sequenceA, then, shifts the tag to the values in the other functorial structure (in the example above, a list).