Are people buying from random home made shops without knowing who is making it? Or are they buying from "Mrs so and so, her husband is in Rabbi Berkowitzs kollel"
I'm not sure what type of products we're discussing, I thought it's prepackaged on a shelf.
Walk into an American-style store in Jlem, there are often products on the shelf listing 'all ingredients are Badatz' and maybe a phone number. That's one product.
Open an advertising magazine in Jlem and there will be seven caterers advertising various products with 'all ingredients Badatz' (and in one case, 'except for J&J cream cheese'). This is very common, at least here.
RYBs is not saying that it is ossur to buy from them if you know them, but he is saying that he holds you can't have a business selling like that, because people who do not have the right to buy (according to him) will be buying from you. You solve this (and some do) by getting a small, cheap hashgacha. That eliminates the 'lifnei iver.' Maybe after that you can say that 'all ingredients are Badatz' - though Rabbi Berkovit's hechsher got upset at that because THEY allowed more than Badatz and that was all they were certifying.
I used an established, well-known and widely trusted caterer for my bris. They were certified by Rabbi Wiener. I don't eat his hashgacha if I can help it (but will eat it lemaan hasholom), but I asked her to use only Badatz and that was enough. (She said okay but the orange juice will be Rubin.) I had looked into her and a bunch of people who knew her personally said she was trustworthy. A few other things I wanted, and she said Rabbi Wiener doesn't allow it, which I was happy to hear and obey.