Well, to nitpick, the first, fourth and fifth example are just variations of the other ones, and they're (ab)using Haskell features - respectively n+k patterns, laziness and point-free programming.
Those features aren't available on every functional language, and they're not really used indiscriminately as shown here on most Haskell code bases, so yeah, I maintain that this page is a terrible example (albeit a very educational and fun one).
Here's a Python version, showing that even on an imperative language there's a lot of ways of doing the same things:
One would still need to know the majority of the functions in Prelude write a useful program, and even more to write an elegant program, since they are abstracted as concepts.
Where as in an imperative language often learning the syntax is enough to get the ball rolling.
Those features aren't available on every functional language, and they're not really used indiscriminately as shown here on most Haskell code bases, so yeah, I maintain that this page is a terrible example (albeit a very educational and fun one).
Here's a Python version, showing that even on an imperative language there's a lot of ways of doing the same things:
https://gist.github.com/289467