[mothered]

Anything of the same weight? So if they won't check what's inside

Not If you don't show signs of Inconsistencies.

And In the event they do open It, plead Ignorance by saying that you've simply purchased their product and returned It In the exact  same state.

someone will buy that package in the future and receive my "returned" thing? Idk about that man.

Who's to say that they're not doing what you've done- an SE'er using the same method?

Once It's placed Into stock, then picked, packed and dispatched, It goes through so many hands and as such, It's a very arduous task trying to pinpoint precisely who's at fault.