The current explanation is related to what Badgerdog said. They do use HIPPA. The other part is if you hear a fire call at 612 Church st. for an unconscious 24 year old female given to Rescue 1 and 15 minutes late you hear Rescue 17 en route to ARH with a 24 year old female who overdosed on take your pick then you have identifiable information about a patient. Maybe not her name but age, sex, condition and reason for condition along with her address. It doesn't take a genius to put two and two together.
Hence you have an excuse to encrypt it and they take it.
Kind of like the old saying "Any port in a storm" only this is "Any excuse to take it"
Also as an aside I remember running into a major jurisdiction a few years ago that would give not only the patient's name but their social security number over the med channels. Don't ask me why but they did. Can't remember where it was as I traveled all over the US at the time. Always shocked me to hear it.
We never did anything like that in LA. sex, age, CC and vitals plus ETA and certain treatment related stuff like O2 being administered or being packaged with full C-Spine precautions, or drugs being administered etc.