I agree, the volume of mail to open is mind-numbing. I just reported what the local clerk told me. It is a small town P.O. so they might be able to open everything "media" in such a location.
I have also heard the "inspections" are random which would be more feasible. I still think it is just a thinly veiled tactic to get people to use the higher priced services. There are some eBay users that are pretty hot about this, the ones who make a living selling DVDs, videos and vinyl records.
I send a lot of media mail as audiobooks on cassette and CDs sold on eBay. I have been grilled extensively at the PO for packages that are light but rattle (cassettes) and thin and light (CDs). Gone of the days of the old bookrate as the only "media".
It is a small town P.O. so they might be able to open everything "media" in such a location.