Don't know how true this is but I've heard fed-ex is much more lenient than ups and usps when it comes to shipping shit like that.
nah du. ups and fed-ex, being privately owned, can open your package for no reason at all. you agree to their TOS, and consequently sacrifice all your privacy for 'security'.
the federal government is only allowed to run a drug dog down the line of packages. since it's a felony to tamper with mail, there are strict regulations on what they can and can't do.
use USPS if you're planning to ship something. package it securely & airtight of course, fake name and real return address.