But there are already passenger services on both routes with the other locos...so wondered why they didn't give any to the 182
In real life only certain locos run passenger services on certain routes. For example, the DB182 did run passenger services on Rapid Transit in real life, but it only ran freight services on MSB in real life. The game is just trying to mimic the real life services.
The Br 182 did actually run on RT but nowadays it is only Used for Regional Express Trains Between Hamburg and Berlin.