Because their schools have nothing to do with USMLE. USMLE is not a requirement for IMGs to be a licensed in their country. Besides, being imGs, they have already graduated! So technically med school's work is done.
I know you were told to make a new thread over here, but in the future, please ask a moderator or report your thread and ask for it to be moved, rather than create a 2nd thread asking the same thing. I have merged your threads together.