I hadn't experienced anything remotely close to package screening when I used to work at UPS (preload shift for a year, quit a month ago), other than packages with hazardous materials labels. The system is so automated that no single worker can really pay attention to specific package details (like addresses, for example), except for the delivery drivers, of course. But they assume that once any package in loaded in their truck, it's fine to deliver. No questions asked, really.