The only fee that students pay that would even come remotely close to what you are referring to would be the Activity, Services, Building and Recreation fee. That covers:
" The activity, services & building fee is a mandatory fee that supports a variety of activities and services for all students. It is not based on whether or not a student uses an individual activity or service. This fee provides several benefits such as student admission rates to concerts and athletic events and, unlimited use of CyRide, the Ames bus system. In addition, the fee provides support for campus recreation facilities, the Memorial Union, and campus organizations and services as allocated by the Government of the Student Body. The activity, services, building and recreation fee includes assessments of the following amounts for each fall and spring semester (full time student). "
The only thing students are subsidizing is the cost of their own tickets.