I don’t know the statistics, but I live in the US, and had rented for 10+ years with 5 of 6 different landlords in 3 cities, and I always got my deposit back, and I don’t know anyone who was stiffed either. But I wasn’t staying in the worst places, but not the best either. One was an informal cash transaction rental from a Craigslist ad and it worked out.
Stay in a slum and you'll find those who are more than happy to break the rules if they know they can.
You probably have the mental fortitude to figure out how to fight back on your own. To read the docs, know your position, agreements, and how to take a landlord to court to win.
In low income, people don't know their rights nor do they ever believe that the system could ever be on their side. And, they're not unjustified in that thinking.
A lot depends on state and local laws. In San Francisco, for example, I get interest on the security deposit my landlord is holding credited to my rent every year. They cannot charge for reasonable wear and tear. So even though the deposit is large, I expect ~100% of it back when I leave. If not, there is a strong tenants union that will support my case.