Once, a courier company that we use sent us a new courier, someone from G-something from Africa. An immigrant. That was not a problem by itself, but - we soon found out that he is quite disgusting - he would not close the door when he was using toilet. He would happily wave and extended hand, as if to shake... disgusting.
If someone is not "advanced enough" to close toilet doors, how could that person be trusted to close the van doors? He was a liability, because he would likely lose the letters we were sending. We had to make the company stop sending him to us.