I’ve been told this everywhere I’ve rented with different reasons ranging from it’ll put undue stress on the sill, liability (non first floor apartment would’ve been bad if it fell out), and the current ones thought was they tend to leak water which can damage the pain and then damage the sill.

Long as the landlord isn’t regularly coming by the property for inspections then yeah fair

Even renting a house it’s in my lease I can’t use a window unit. Which sucks because our swamp cooler outputs into the living room in a way that makes it very difficult to get its air into the second bedroom.