You have to put together all the elements I'm quoting :
- Taxiways should be completely invisible from the air. But at SFO they were very visible.
- A runway with complete lighting (approach lights, papi, touchdown zone lights, centerline) is easily distinguishable from a taxiway (even if lit)
- But airports often wanna save pennies and turn off approach lights, centerline lights, and touchdown zone light
- In these conditions, a runway is only left with papi, edge, and entry lights. And now a runway like this is closer to a lit taxiway.
- The safety margins are now reduced because a lit taxiway resembles a poorly lit runway
- But it still takes fatigue or another aggravating circumstance to mix up a white runway and a green taxiway
Plus there were other cues, visual or instrumental.
The crew should have expected a taxiway to the right of the runways.