Having worked for UPS for years in a department that handles just this type of thing. If the address tag is gone or unreadable we opened it looking for an invoice or a cod slip with a price,correct address etc.I can tell you I have opened many many packages in my time. When you are dealing on such a tight schedule with shipping times, There isn't always time or even access to computers to go and look up hundreds of packages that come through with mistakes on each shift. Opening is usually the quickest and most efficient way as 95% of the time there is an invoice. I have seen many very personal things but the main objective was to get the package to the customer asap. Not to be nosey. These companies want you to get your goods with as little hassle as possible. It's either get your package to you or send it back to the shipper and let them handle it. Parcels shipped thru UPS or Fedex is not considered mail. I'm not sure about Fedex,maybe they have a different policy than UPS. Personally,I would rather have them do whatever they had to do to get my package to me on time without any mix ups on COD price,wrong address, etc.