A global is a global, and wrapping it in a 'singleton pattern' and having to make a long-winded, slow and repetitious call to get your hands on it each time you need to use it is pointless.

Well, you don't have to make the call everytime - you can just call once for each logger you need and cache the result. The fact that get_logger($logname) always returns the same object for the same logname is just a convenience. It has very little to do with object oriented programming (except maybe for the terminology).