What's really neat linguistically is that "helicopter" isn't a compound of "heli" and "copter," but rather "helico" (as in helix, helical) and "pter" (as in pterodactyl).
"Rebracketing" is when this happens (i.e., the split in the word is moved in colloquial language).
Honest question, are there any reasons why a private citizen performing this sort of thing would be legally less of a problem than the state?
From a philosphical perspective I'm all for catching mail thieves. But I would get a little twitchy hearing that the police are mailing tracking devices. And I would be more or less ok with a private citizen helping to "catch the bad guy" with their security camera, but I do not want police surveillance cameras on my street, thank you very much.