I believe for day trains like ICEs, the GEN compartment must be like GEN of long distance trains vis a vis bays with luggage racks. That type will hold more people. People will be seated on luggage racks, cramped inbetween the 2 long seats. Some even seated in luggage racks above the side seats. The general capacity is much more than this.
Here just 6 per row and very little place to stand, also no one can squeeze onto luggage racks :)