Thanks for all the comments - what I have concluded from my very brief experience in open is that Elite is two completely different games.
1. In Mobius / solo. it is a game with:
rules: NPC's will try to steal your cargo, but they won't just open fire for no reason or if you have nothing to steal.
etiquette: NPC's will hail you and warn you before they try to steal your cargo. You can take the decision to fight back, give in, flee.
sportsmanship: NPC's are generally ranked to your combat skill. (similar to a Golf handicap where you could play and have a fun game, even against Tiger Woods)
referee: In non anarchy systems, the system security forces may eventually come and help.
calculated risk: e.g. Since I generally can only play relatively short sessions, I am always getting attacked while mining. I recently tried to fight back in my mining ship with lots of painite onboard, but it turned out it was not just the normal 1-2 ships, it was a wing of 5 that attacked and killed me. That was an expensive learning experience too.
2. In open, it is not really a game. It is a free-for-all with:
no rules:
no etiquette:
no sportsmanship:
no referee:
unknowable risk:
I was in Shana Bei, a "High Security" system for the CG - but in the <5s it took for my 6C shields and 3 x shield boosters to vanish, I briefly saw a message that system security was on the way. Thanks a lot Fdev
I am not complaining, and I wouldn't report the CMDR for cheating - it was quite probably a legit "kill" and the CMDR can proudly hang up another "harmless Type-9" trophy onto his wall. He role-played psychopathic serial killer to perfection.
I was merely disappointed, since I have seen various forum posts and You-tubers saying what fun they have had in Open, so I wanted to try it too. I knew there was a certain amount of risk going into open and I obviously underestimated it. If I had known about, and had time to read, these sort of thread's beforehand then I might have been better prepared !