I believe all of this but also want to say that in my life as a renter I never once had a landlord return a security deposit without me taking them to court. There's definitely some ruthlessness.
Interesting, but on the other side of the coin I can tell you that in 10 years of renting I've only foregone small fractions of my deposits and always by choice (pre-departure inspection tells you what they'd charge for anything amiss, and you can choose to clean/fix/etc. or pay them out of your deposit). If you don't get a pre-departure inspection you're definitely set up for ambiguity and shadiness.
In one apartment, I even spilled some bleach in a closet, and sneakily replaced the piece of carpet from the scraps I found when they were recarpeting a nearby unit. They didn't notice or care.
I've been a perfect tenant my entire life, and I was still always treated like trash by every landlord I've rented from. I don't think they make a distinction.
