Sorry if I didnt make myself clear. All dictionary definitions of Carjacking I can find define it as the theft of the whole car whilst the driver is present by force or threats of violence - (or forcing the driver to take them somewhere.) Its this which IMO is unlikely with the Jazz , but more of a risk with High end cars such as Range Rovers. At least in the UK.
But I wouldnt call a smash and grab of a bag etc whilst you are in the car a carjacking. Its more like a bag snatch or street Robbery/mugging which could also happen to a pedestrian. Frail OAP's walking with their tempting handbags and " 'this is where I keep the valuables" bumbags should also beware. Especially if obviously tourists. And the law regards thefts from unattended cars differently and less serious.
Police now count 'vehicle theft while occupied' as classed in with 'jacking' (my daughters husband works in policing in Brum). You are right in your assumption regarding theft of the vehicle, and who really would bother nicking a Jazz? (unless the spare parts market starts getting worse, then we all know how expensive Honda parts are).
The issue with stealing from an occupied car is vastly different to a street mugging. They can target people by stealing more than just a handbag or bumbag. Think what people carry with them when travelling to work, from shopping etc. The other thing is surprise. Mugging pedestrians offers the possibility of violence to the thief and other members of Joe public stepping in. By opening a car door/tailgate and making off gives you the problem trying to assess what has just happened, of unbuckling your seatbelt, opening your door, climbing out and then wondering what you're going to do with your car while sat in traffic before chasing the thief... who invariably will be on a leccy bike or scooter.
Now, if I am carrying anything of value, it is hidden in the boot (about 6k worth of bird spotting scope/binoculars)... and I manually lock the doors upon driving away.