I've sent flash media through mail without problems. As well as hard drives with disks. Never had an issue.

I would assume that mail scanning is similar to the x-ray scanner at the airport, and any SD card or hard drive that cant handle that is useless.

Could you imagine having your laptop and camera wiped every time you jumped on a plane.

Film is mailed all of the time without issue. Film would be ruined by the luggage scanning (i.e. higher power) machines though most film is usually OK with the lower power carry-on scanning machines.

TSA opened my checked luggage to manually inspect the box of 9-track tapes.