I recently had some work done in my home. Since I had to remove all of the items that were on the top shelves of my garage, I was intimately familiar with almost everything I had to take down. Unless you are prepared to stand with the vendor every minute, you are going to lose some of your merchandise. When I cleaned up after vendor left I was missing at least two lamps that were stored on the top shelf.
These were two items (lamps) that were hard to miss sincre I put the 4 lamps on the floor the night before. No, I did not see the vendor take them. They were there the night before he came and were missing when he left. Use your imagination.
As an aside, I used to have a housekeeper.. I had just returned from $ Tree, purchasing two cans of furniture polish the day before she was due. It cost me $2. When she left the house I was missing both cans. I called her immediately and her reply was "I will bring them back." I told her to keep the polish and don't come back.