Someone asked me on here about coop buildings.

It’s a concept pretty unique to some US cities with old building stock. In NYC, pretty much all non-rental buildings older than the 1980s are coops.
Now, when you buy an apartment (a condo) in a normal new building, you end up owning it. If you buy an apartment in a coop, you just own shares in a corporation that entitle you to living there. For example, if you and a few friends decide to pool your money together and buy a small building, you would form a coop (a corporation), and decide among yourselves who gets which apartment, how you would split the upkeep costs, who cleans the snow outside in winter, whether to allow pet snakes, etc. The corporation that you would form then would take out a mortgage from the bank, rather than individual people. There may be an empty apartment or two that you might rent out to offset the costs and help pay for the mortgage. Having this arrangement helps you define ahead of time what happens if you decide to sell or move and rent your own place out, etc.
Because you co-own the building with friends, you have a lot of interest in who else might live in your building, and whether you can trust them as much as you would your friends.
Some of the best buildings to live in NY are “Finnish coops”, built by Finnish working-class immigrants in 1930s – since they built them for themselves, no corners were cut, and they are really high quality.
In bigger buildings, they elect coop boards to deal with day-to-day issues. Coop directors are unpaid – they typically have day jobs and families, and must be highly trusted by everyone else, since they’d also be managing the collective funds.

So, these coop boards get to approve who the new renters or buyers are. They are not accountable to anybody, and although this country now has anti-discrimination laws, nobody ever has the money or desire to sue the board to be allowed into the building (even if you win, do you really want people who didn’t want you to be your neighbors?). There were a few exceptions, typically celebrities trying to get into exclusive NYC buildings (and nobody wants celebrities who would disturb the peace as neighbors ). NYC board interviews are dreaded, and there are extensive recommendations on how to pass them (unlike job interviews, you must say as little as possible, and the more boring you are, the better). They are also far more stringent to their buyer finances than most banks are – which is also why NYC escaped the financial crisis of 2008-09 so relatively unscathed.

Coop apartments tend to be less expensive than condos, because they are so much harder to buy and sell.

R’s building has a twist in that it’s income-restricted. In the 70s, NYC came to own a bunch of derelict buildings full of poor (and typically black) people, from landlords who were neglecting them. Instead of spending city money (NYC went bankrupt in the 1970s), and the city being a landlord, keeping up the buildings and collecting tiny rents, the city decided to just convert these buildings into coops and “sell” these apartments to their tenants, typically for symbolic amount of $200-$300 per apartment. The thinking went that since these poor people were now owners, they would take much better care of the buildings themselves. To prevent investors swooping in and buying these apartments and abusing residents, the city government imposed additional rules, like you couldn’t make over certain amount to buy there, and huge “flip taxes” on profit of anyone who tried to sell these apartments (that went back to each coop). And there is a special city department that oversees and enforces all that.

Unfortunately, since these people typically have never owned anything substantial, and nobody bothered to educate them on responsibilities that come with ownership, many of them continued treating their buildings like renters, often not paying the fees into the common funds, calling on city inspectors when something was broken (who would then issue fines), instead of trying to fix it themselves. So, many of these buildings declined further. Boards could be corrupt, too. Some buildings fell behind on taxes, and when the real estate rebounded in the 90s and 2000s, the city would confiscate the buildings, sell them to the developers and kick their former owners out. That it is a major driving force behind gentrification in Harlem and other historically black neighborhoods in NYC.

R’s building escaped that fate largely thanks to the efforts of some of its newer residents who bought their places in 2000s for far more than the $300, but the resentment towards these new (typically, but not always, white, asian, carribean and african-european) residents, is unfortunately stronger than ever. Being tied into the nasty US race tensions along with other inequalities doesn’t help things either.