however, how can you justify 'ghosting' past dangers others with expansions HAVE to face whilst being rewarded from the same market?
Because there IS no shared shard. ED is, first and foremost, a singleplayer game with multiplayer options and the seamless integration thereof, "mingleplayer" if you will. If you choose to let your savegame do so, it will connect to the central server to upload and download important things like changes to market prices or nation borders; i.e. how much a ton of steel costs or who owns what planet at this point in time. It will even, rather like Minecraft, allow others to join in, depending on your preferences and a few parameters; one of which, I can guarantee you, will probably be the presence or absence of expansions.
All Online connects to the central server and lets others join in with the only limit being the matchmaker's parameters and any blacklists you have.
Private groups connect the central server, but only allow a select group of other players join in by invitation only.
Solo Online connects to the central server, but doesn't let anyone join in, under any circumstances, ever. This is probably the closest to this 'ghosting' that you talk about, since you don't deal with other players at all, but still get the evolving galaxy. Mind you, it's built into the game from day one.
Solo Offline doesn't even connect to the central server.
Other players take the place of, and in turn are replaced by, NPCs, seamlessly. If you let them. Other than that, however, your game, in all the ways that matter, is self contained and separate from anyone else. Your copy of ED is just that: a self-contained copy, not a client connecting to a game stored on some server somewhere. Dead Island does something very similar. I suggest taking a look at it.
That's why Solo Online can exist. That's why Solo Offline can exist. That's why it doesn't matter whether I buy the avatars expansion or not. Because it doesn't affect your game.
The expansions supposed to expand the scope of the game by allowing you to do more
if you so choose. Not replace or override the base gameplay. Avatars ADD ways to get missions, steal ships, and other such activities, on top of the gameplay that is unique to the expansion; they do NOT become the one and only way.
I'm fine with lists and UIs, and I'm bored to death of shooters. Hence, the avatars expansion doesn't interest me. Hence, I won't buy it.
But my not having it doesn't affect you. In any way.
Your mistake (and mine too until recently, I'll admit) is thinking of ED as a multiplayer game with optional singleplayer. It makes much more sense if you look at it from the opposite perspective, as a singleplayer game with optional multiplayer.
The "play your way" motto doesn't just describe the gameplay. It describes
everything! It's quite brilliant, thinking about it.