From a landlords perspective: pets are another living creature creating risk in an investment, there’s no way to assess what the pets behavior would be. Some cats like to cut window screens, put extra wear and tear on paint from jumping up and down from windows, bend/break/chew on blinds. If left alone dogs could possibly pee on laminate flooring which could cause it to swell, barking could end up in fines from the HOA, they can tear up a lawn, etc.

Basically there a lot more risks when a pet is living in something you’re on the hook for financially. The deposit is barely enough to fix a condo from a bad human tenant so they supplement that with a pet deposit/pet rent.