I've always been surprised that landlords routinely return security deposits in full. After a decade of renting in multiple cities, I've always received 100% of my deposit back, even in cases where it probably would've been fair to charge me for some minor things (holes in the wall from hanging things, some small stains, etc).

There are penalties in some cases (the letter in this post says in Georgia if you get caught there's a 3x penalty), but I've never heard of those actually enforced.

In other words, there's a lot of incentive for this to happen all the time, especially since landlords don't have much of an online reputation (like restaurants). The fact that it's rare in the US is a great sign for doing business here generally.