I just got my GPRS radio license and this was a really strange phenomenon to encounter. Apparently the FCC doesn't allow actual encrypted comms in this part of the spectrum, so the "privacy" codes, like you said, are really more just convenience codes, more noise cancelation than anything for privacy or security.
It was weird trying to explain this to my family, too. Basically just had to tell them "Nothing you say is private, and you should all say my call sign at the end of each transmission." We all felt like dorks, but it was super convenient in a place with no cell service.
It was weird trying to explain this to my family, too. Basically just had to tell them "Nothing you say is private, and you should all say my call sign at the end of each transmission." We all felt like dorks, but it was super convenient in a place with no cell service.