You don't know how many of those guns may have been sent in for custom work. I just sent in a S&W revolver for custom work.
You don't know how many were sold. You don't know how many may be going back to the factory for repair after possibly years and years of heavy shooting.
As for kel-tec, well, some people have problems with them, and some people are mechanically inclined. Kel-tec keeps their price down by skipping some of the more expensive and labor-intensive finishing operations. Those finishing operations are not necessary on 100% of the guns - most run fine without them. But it is left to the end user to do such finishing if required. It hasn't been on any of the several Kel-Tec pistols I've owned.
It should be expected, and little research is necessary to determine that it is the case. You can't expect to buy a new semiautomatic for less than $300 and expect it to be perfect without having to do any work on it. What's the next best gun cost? How is the quality of other guns in this price range?
I was able to afford a Glock, S&W, Browning, etc. I carry those over the Kel-Tec. But when I was poor, I bought a Kel-Tec and (would have if necessary) made it work with little more than sandpaper and a few hours of my time. I've since sold all of them but my P3AT which is quite accurate and aside from one loose pin which was fixed with loctite in approximately 20 seconds, has performed flawlessly.