I have to say that when I started playing Elite, I watched some videos about the engineering and most of them say that with non-engineered ship you don't have a chance vs an engineered one so I didn't want risk losing my ship and played in solo for about 3 months. I found a nice system under the influence of Felicia Winters and did all sorts of things from there. Then one day I just logged into Open, I went really carefully, watching my radar for indication of players, I was really on high alert all the time and then it happened - I played in Open every day for a week and hadn't met a single other player. I always play in Open now and after my 1000+ hours I have randomly encountered about 30 players out of whom only 1 attacked me. I am now in a Squadron, I keep flying in "our" space on Open and unless we wing together, I don't encounter players very often...or actually, I think I haven't encounter any player outside of a wing.
The thing is that once you leave the bunch of systems you start in, you can just find some system at the edge of the Bubble and your chances that you bump into a player is close to 0, eve less so into someone who will try to kill you. Obviously, there are places where you are almost certain to encounter other players such as Engineer bases, Community Goal sites and those stations that offer all modules for sale but you can avoid those places if you don't wanna interact with players. The only place where I got attacked and destroyed was actually an Engineer base where some jackass waited in upgraded ship and kept shooting down players who got there but once I got destroyed in my un-upgraded ship I went to a station, picked up my upgraded combat ship and went back - I only found another commander who was looking for that jackass too, so we kept patrolling there for about 15 minutes, had a cool chat together and then we left. So the problem sort of solved itself.
I understand that people don't wanna risk getting back from several thousand LY long expedition just to get blown up in the bubble and lose all the credits - I was really nervous about this very thing when I first went on a 10K LY expedition but I encountered noone on my way back. If you wanna avoid other players, then, unless someone is looking for you and knows exactly where you are, the chance you run into a player is really extremely low.