Part 1 of 2. The answer to this question will take some time, as there are many misconceptions regarding Kosher and non-Kosher (or non-certified) cheese. In addition, the Kashrut industry controls both the supervision on production and the halakhic literature, thus creating an exorbitant pricing system in which what is considered a “strictly” Kosher cheese, of rather inferior quality, could cost twice or three times as much as a similar “non-supervised” cheese.
This creates a considerable economic interest in preserving a state of affairs where “non-supervised” cheese is deemed non-kosher, despite the difficulties it creates for observant Jews (as I have mentioned in other articles, one cannot brush aside the cost factor, since the Talmud stresses in many places that we must not cause people to spend more than what is necessary.)
The above is from Rabbi Ovadia's daily emails on Halakha. To join the list, please email firstname.lastname@example.org, your full name, location and a little about yourself. It's free to sign up.