Because the CW9 or CM9 costs about $250 less than a PM9 and its the functional equivalent of the PM9, just uglier.
You are also comparing apples to oranges.
CW9= less expensive P9
CM9= less expensive PM9
Everyone gets all worked up over the PM9/CM9 when most people would be better served by the P9/CW9. The larger guns are the same size as a shield.
So if you want to compare apples to apples, namely a slim 9mm with a grip large enough to get your whole hand on, the gun to compare with is the CW/P9
Remember one thing. Unless you are going to carry the PM9 in your pocket, it is almost universally inferior to the P9. I know. I've owned both and also an intermediate itteration that Kahr made in the late 90s called the P9 Covert which had a P9 slide and a PM9 grip.
My first polymer framed Kahr was a P9, then I got the covert, then i got the PM9 hoping to pocket carry it. It proved to be too heavy for me to pocket carry so I ended up carrying it in an IWB I still owned, from when I had the P9.
The PM9 is no easier to carry than a P9 in an IWB holster and its more difficult to shoot well and holds one less round. So my point is that most people do themselves a disservice by immediately and reflexively gravitating towards the PM9/CM9 when the P9/CW9 is probably a better choice. This is ESPECIALLY true of women or men who have diminished hand strength since the longer slide of the P9 tames the recoil a bit and the longer grip allows you to get your pinkie on the grip. (This obsession that men have with buying women cute little guns is another pet peeve of mine, but that is another rant)
Thank you. That's a lot more about the different Kahr models than I knew previously.