Even without bandwidth monitor (in game or on the hub or router or on the computer) and without rubber banding it's possible to identify human players.
They simply fly differently in SC than NPCs. A player would have to study the way NPCs fly in SC and mimic that behavior to make it harder for a hunter to identify that player as player.
And even if it would really be impossible to distinguish between humans and NPCs in SC. In normal space NPCs behave completely different.
And even if they would behave in normal space the same as NPCs. It doesn't matter if a player killer has to kill 10 NPCs to kill one player. The reward - assuming to have killed an other player - is there.
And then we have those players who don't attack other players, but do attack clean NPCs.
But having to identify humans by the way they fly is a skill, and that would add something to the game. Right now, it's obvious - look, there's a hollow square.
Incidentally, if you watch NPCs in a system for a while (I have done so), a lot of them jump out at the star and head straight to a space station. Exactly as a human trader would do.
Players are members of the Pilots Federation. NPCs are not. You could argue that this differentiation is just an excuse for the hallow square.
It is.
Anyway. A dedicated player killer is a much higher threat than an NPC. The player won't wait a few seconds. The player won't scan. The player will have highly modded weapons.
The level of threat is irrelevant.
I've been attacked by NPCs that don't wait and have modded weapons. Admittedly, player enemies are more dangerous - but that just adds to the game, surely? Can always escape to another mode...