Some places charge more per month, some don't. Since I don't keep critters, I really don't know what they do here. I think they just found a way to exploit a loophole in the Landlord Tenant Act. My neighbor who went back to California the end of June had to pay $40 for carpet cleaning, half of what the mgr. said it costs them; she'd been here two years and lots of places don't (maybe legally can't) charge for carpet cleaning or repainting after three years. The carpets here need to be replaced anyhow.
I should never overestimate my basic arithmetic skills.