Secret but not interesting
Most of what the govt. produces is "secret" in that they don't want anyone to know anything about what's going on. So many of the USBs will contain boring and pointless documents.
Also, losing so many documents is part of a secrecy strategey.
Some of the 'lost' disks/USBs/Laptops should have been deliberately 'lost' and contain disinformation. It's the "Raiders of the Lost Ark" principle - lose so many USBs that no-one knows which one contains the really useful information. If not, then they need to sack the head of the secret services and employ me instead.
Any seriously secret data would be encrypted - so no problem. If it wasn't, then see suggestion in previous paragraph. I'm available to start on Monday.