I don't know if anyone else has commented on this so far, but here are my findings regarding NPC spawning in "real space" (non-supercruise):
At belts or rings, even in very, very remote systems (the Pleiades Nebula is absolutely writhing with activity) NPCs will start spawning at your location, regardless of that system's supercruise traffic (or lack thereof). Sometimes it will be police, and they will do their routine scan ritual. Most of the time it will be pirates, who will scan you and, if you have no cargo, hang around for ages, repeatedly scanning you as if they have no short term memory.
Eventually, the pirates will leave, and the spawn system will kick in again; once again, it can be police, pirates, or very rarely a psychotic NPC who will attack you on sight.
If you start flying in any direction, and just keep going at top speed, NPCs will keep spawning at the edge of your sensors. They will try to follow you, or leave, and spawn again. Over the course of 15 minutes, I witnessed literally every type of ship spawning on me in a remote system.
Additionally, miner NPCs appear to be broken. I witnessed two different mining teams (a lone Asp, and a Type 6 with two sidewinder escorts) do some pretend mining (no chunks of rock ever appeared, but the ships pretended to scoop them anyway)... and then all four ships flew away together, parked a few hundred meters from the rocks, and sat there.
For an hour.
I rather find myself looking back at X3, and remembering with great fondness the impressive scale and persistence of AI activity. Ships in that game would not only have objectives, they actually did complete them without pretending - watching a trader NPC dock at a station, you'd see the quantity of goods at that station take a big dip as the NPC bought a load of them. Similarly, your stations and assets could be attacked when you were in a completely different system. Freelancer had pretty good AI too, with ships whose pilots actually knew where they were going and where they'd come from, and could tell you.
Elite certainly has some growing to do.