Got to love the button fly commentary. I like my button fly Rotas and tend to think button fly trousers look a bit better when one is seated than ones with a zipper. It's true that they take a few more seconds to undo and redo than a zipper would, but that's usually not a big deal. That said, who seriously has ever injured themselves with a zipper? I think that safety argument is sillier than the convenience argument, which at least has some validity and application to everyday life.
If anyone is having that many issues getting a button fly open before pissing at a urinal, then the fly is not your biggest problem, maybe you need to see a urologist. You're looking at maybe 3 seconds max with a button fly as opposed to 1 second with a zipper.