I can see why they don't allow it in some countries. It pretty much let the car be a surveillance device with multiple cameras. If I park my car in front of a store or a house, I could turn on my phone and start screen recording and recording everyone goes in and out of the place.
I found the live sentry quite handy. Sometime I forgot to close my garage door when I leave the house in the car parked in the garage. I don't have a smart garage door so when I have that "did I close the garage door moment", short of driving back, the only way to check is to live view the side camera of my other Tesla that parked at the driveway. It points right at the garage door.