Unequal distribution, basically. While most planets will never be observed by a human, it turns out players congregate in certain parts of the galaxy, particul

Unequal distribution, basically. While most planets will never be observed by a human, it turns out players congregate in certain parts of the galaxy, particularly near the galactic center. (The game starts you at a random location near the edge and there's literally a 'reach the galactic center' quest, so most players end up near the center eventually.) So yes, there are trillions of stars, but there's only so many of them within $RADIUS of the center. In practice every planet 'near' (for some definition of 'near') the center has already been discovered and the 'good' planets are likely to already have bases. There are also spots that get their locations published in the forums or advertised in-game (good drops, cool bases, things like that) that also end up 'locally' crowded. I found there were basically two experiences in NMS - "the outer rim" which was, frankly, lonely - you almost never encounter any signs that other players even exist and "the core" where it feels like everything has already been done - sure it's new to you, but you're never the first. Finding a middle zone where you can see evidence of other players, but there's still stuff to discover was rare in my experience.