There wasn't a "cheap and chintzy building owner" involved. It was a condominium. Owned and maintained by the residents.
The building sat on top of deep pilings, sunk into limestone. I imagine those pilings are completely intact. It was the area beneath the pool deck which has most come into question. Corrosion, cracking, spalling...
Something caved into the basement/parking garage below the pool deck and the rest pancaked down on top. Nobody in the 80s was taking any special precautions about protecting re-bar or special additives to strengthen the concrete in cheap-assed condos.
Regulations and building codes were lax back then. Not so much anymore.