That's not true at all. Registered mail doesn't have to be inspected to be sent. I don't know where you got that information, but it is very wrong.
I use registered mail on a regular basis for high value metal sales, as thats the only way to insure silver bullion if its being shipped. You have to package it in front of the post office employee, and they make sure that the package is sealed correctly, and you are shipping what you said you are shipping.
Is that maybe because of the insurance you are adding to it that they have you do that?