At first they pay more than German students for the same semester, despite having worse chances to succeed (language barrier, culture barrier, fewer friends/family etc). Then they have to join preparation courses one way or another, because, you know, German isn't easy. Then they hardly get access to the public student dorms and are put 3-6 people in old, unclean apartments far away from university (partly without public transport access) and EACH of them pays as much as a German would pay for the whole apartment. Professors also have huge power over them and in some points can even enforce them indirectly to return to their home country. Old dudes (teachers, profs, organizers) dating barely legal girls in exchange for favors also is accepted practice.
Sure, the official part of everything they have to do and pay to succeed may be the same as for Germans and none of the "fees" may be labeled as such, but studying in Germany is much more expensive for foreign students than for Germans.