Uh, Google's main job is to rank results according to what other people find helpful. There is no truly objective way to do this. The closest you can get is to define "objective" the way pollsters do, as a way of understanding average opinions.
What does "average" mean here, though? Do you rank restricted sites higher if more people have accounts?
They could probably do a better job if they knew what you're subscribed to. For example, people with a Quora account or Washington Post subscription should get that ranked higher. But this would mean telling Google more about you, which seems to be unpopular around here?
It's not that complicated. Google indexes webpages. Webpages are identified by a URL. If, for any client, without any context or previous interaction, the URL results in anything other than the indexed content, it should not appear in search results.
If a webpage requires login credentials, which the crawler obviously does not have, the crawler should have received a login page.
What does "average" mean here, though? Do you rank restricted sites higher if more people have accounts?
They could probably do a better job if they knew what you're subscribed to. For example, people with a Quora account or Washington Post subscription should get that ranked higher. But this would mean telling Google more about you, which seems to be unpopular around here?