The large amount of cars in that area is because of the sororities meeting every Monday evening.
Unless one side of the street is marked as a no-parking zone or has a sign about not parking from the sign to the next curb, there are no restrictions about parking on both sides of a street. This is pretty standard everywhere, not just here since street parking is public parking.
Additional violations could include parking facing traffic, parking within a certain distance to a stop sign/intersection, or parking within a certain amount of feet to a fire hydrant. These are state laws as opposed to the no parking zones which are city ordinances.
If a car is in fact parked in the middle of the street, this is indeed a violation as well. I'd encourage you call CSPD non emergency number for any of these violations (979-764-3600) so that the car can be towed or ticketed. Keep in mind that unless a car is literally blocking a road, it is a low priority call, but will eventually get handled.
Additionally, a call to TAMU Greek Life may not be a bad idea to express your frustrations. I live in the area as well and understand. Maybe if more people expressed their frustrations to the right authorities, there would be something done about it.