"End-to-end encryption is easy - you just need to send a courier with a one time pad."
Key management is a PITA. Still, making pairs of DVDs filled with random noise isn't that hard. If you seal them with glitter nail polish and send a picture of the sealing back, then you and the recipient can be fairly sure it wasn't intercepted and copied.
USB sticks are larger, but you need to completely erase the USB or DVD after copying to disk. Then the program needs to enforce that used blocks on the disk are erased.
Phil Z and one other name in the crypto biz thinks this is unneeded.
It doesn't work well for encrypting pirated movies, but for most stuff it's really secure.