https://en.wikipedia.org/wiki/Informed_Delivery
https://informeddelivery.usps.com/box/pages/intro/start.acti...
The USPS already scans the exterior of every letter they deliver (perhaps a result of the 2001 anthrax attacks?). They let you see the scans online. You don't have to "speculate" about losing mail.
The privacy implications suck, but c'est la vie.