“I heard from some anashim peshutim from there that they had hard time adjusting to American kashrut.”
Nobody says that the cholov stam heter applies in Iraq; that’s why I used it as a non-controversial example. Your Iraqi friends simply didn’t keep kosher.
Simcha:
I was given this psak as well regarding shmitah i.e. that if I end up with heter mechira produce somehow, I’m not even allowed to pawn it off on someone who holds by the heter due to lifnei iver. I’m not noheg like this with cholov yisroel, but it would be totally understandable if someone were. I’m not sure why this is so hard for people to understand.