For example, 90% of the time, delivery drivers know what's inside a package. Knowing that, it's a matter of sizing up the house it should go to, and when you think about it, is not hard to figure out.
Say John Jones lives at Route 2 Bx 44, which is among a cluster of house on a hill. John's package is coming from Bass Pro Shops from Springfield, Missouri. Such a package would most likely go to the house with the bass boat sitting in the garage or at the side of the house in plain view from the road.
When you're on the job, the task of finding, verifying, and then delivering the parcel is never too difficult... or too easy.