If you are going to have a gated community, have controlled access and you wouldn’t have so much crime in the first place. This place offered the illusion of security but let everybody and anybody walk through.
Lots of places have security guards and burglaries, including luxury condos. This was a working class condo complex with insufficient funds to pay for full-time security, which would probably run into the hundreds of thousands a year, including liability insurance, adding a couple of grand to everyone's annual HOA fees.