This is enabled by the profound otherization of the residents by the rest of society.
I’ve recently “escaped” from what I have started referring to as a penal colony for people aged 55 and over. Many of its tenants there have physical impairments; most were much older than I.
They aren’t like naughty five-year-olds, but that is how they often get treated, and/or as if they all have dementia.
Most older adults do not have dementia.
(Off the top of my head, I think it’s 1 in 8 if you are over 60. It means that 7 out of 8 people my age do not have dementia at all.)
I mistakenly thought that this was essentially a regular apartment, just with an age restriction. There are similar restrictions, for example for families with children for some housing. I was number 1 on a waiting list of 2600. I needed a place to live (and the other place that I looked at had a major issue that would take an indeterminate amount of time to resolve).
The level of contempt that I was exposed to on account of living there – my address – still brings tears to my eyes. This came mostly from staff at the real estate outfit that owns and operates the building and staff at the local municipality.
When staff belittles and scolds tenants as a matter of habit, and tenants are supposed to keep their mouths shut at all times, this opens up the way for criminals to move in.

Who’s going to believe anyone who dares speak up? Who dares speak up if residents are taught to keep their mouths shut? What use is speaking up if anything you say gets ascribed to your “dementia” anyway?