The problem is that many Ethiopians "buy their visa" to come here. They think this in such a way they are free to work anywhere at anytime. Their sponsors usualy report to the police that they are "run aways", so as to clear their responsibility.
They walk around without a passport, alot of them also do not know who their sponsors are. They only know the "middle man" that got them here.
Because most of the Ethiopians who come here are domestic helpers, they are not aware of how critical their legal status is.