i guess they use either one. my g23 came factory installed with trijicon, and my g26 i bought last week have meprolight. but the meprolight has the glock logo printed on top of the front and rear sights.
I've never felt the need for a night sight. Too much time wasted trying to find 'em in the dark. I'd rather practice my point-and-shoot skills or maybe go to a laser sight. Most police shooting are done at close quarters anyway. From my standpoint night sights are pretty to look at, but that's about it. Oh, I forgot... they will increase resale or trade-in a few dollars. But otherwise, they just run up the price of the gun. That's my opinion, obviously, and other people might feel differently.