For the first film: Why did Eric and Shelly's apartment still have police tape over the front door one year later? Police investigation of the scene should be long since done. I can understand there being no interest in fixing the place up and renting it out again, but over the course of the year there hadn't even been a single prospective squatter or looter who would have torn the tapes off?
As far as squatters go the whole reason they were murdered was for resisting Top Dollar's attempts to remove everyone from the area. It's reasonable then that no one would have returned to live there, even illegally. However the tape should have still been removed after the scene was opened at the conclusion of the police investigation.