The people in charge of testing for contamination have no idea what they are doing. I have a limited view of this, but from what I've seen they don't know what they need to test for. They don't have proper procedures in place of they get a positive test. Lastly they don't seem to have proper monitoring of their facilities to begin with.
It's both because homeopathic remedies are pretty much useless and the people that make them have no business being anywhere near things people put in their bodies.