Anyone working that house would have known what an easy mark/target they had. They would have spent time on the property, seen the seclusion, see that everyone kept private, no neighbors had sight lines to the yard/house, the vegetation providing cover, the night darkness due to the ordinance.
Then the victim; an elderly lady w/ a pacemaker, some mobility issues, with hearing aides, living alone in this environment. We're starting to get more of a complete picture of limitations here. Surely any worker with interaction (getting a bid, getting instructed about the job, working on the property for 2 hours, etc.) would pick up on some of this. And if the worker wasn't directly involved they talk, an associate, cousin; "Man, this old lady is living alone on this big private property with no dog, no real security, and her daughter is that rich TV person."