I received the following reply from Kahr/Auto Ordnance about why the Parkerized 1911s are no longer shown on their website:

Thank you for your question!
Unfortunately, we are no longer producing the PKZSE models for the 1911's.
They are being replaced by the BKO models.


As enthusiasts know, the GI models were blued prior to 1940, then Parkerized during WWII production, returning to blued after. The BKO models from Auto Ordnance, which have outstanding reviews and seem to be great guns, have a "black oxide" finish.