I stand corrected. I was focusing on the killing part of it, where there really are no differences. As I tried to clarify in my last post, there are differences in product selection after the killing process (e.g., not even trying to make the thighs kosher, for the most part). But there is no difference in the raising, the handling of the live birds and the killing, and not a whole lot after that.
I will accept it from you that one doesnāt have to be a rabbi. I only know that they were. Apparently if the product is passed by a rabbi it lends a bit more authority or perhaps cachet. I recall, for example, buying some wine from the Golan Heights. It was certified as kosher and Mevushal by the chief rabbis of Tiberias and Galilee.
Not to go too far afield here, but I bought it as business gifts, and one of the recipients is Jewish. I was cautioned that if he was an observant Jew, and if we were to drink it together, he could open the bottle for me and pour, whereupon we could drink it together, but I could not open the bottle for him or pour, or he could not drink it. I was told (and I assume correctly) that was because the wine was not pasteurized, which many or most kosher wines are. Possibly you are familiar with that particular winery. Yarden. It was very good wine, I must say. Very professionally made.
I understood the reason and was not offended. Religious rules are religious rules. But it did bring home to me how exacting kosher rules can sometimes be.