Huh, I didn’t know there was a knurled variety until now. My guess is that the knurled one is newer.
I have a couple of ratchets which are close to 10 years old that have the lines, which is probably fairly close to the start of their production, I think
Also, looking about the web, it seems like a lot of the product photos from vendors show the k ruled one. I’ve not seen a pic of a knurled one IRL yet. My bet is that they are very new.