They have to submit an application to install a vent fan. 
Are they not allowed to install a vent stack?
They were asked to submit a
retroactive application to "install" a fan that had been in place for three years, and which
replaced an existing fan that had already been there for several years prior.
The inmates are running the asylum
Ditto for the Michigan case. The Fair Housing Act doesn't allow discrimination if you are renting out the entire house or apartment, but it has never (to my limited knowledge) been applied to roommate situations.