Where's the bias?
1 and 3 seem obviously true. There are multiple trials separated either by geography or time, and they have enough failures / successes to make our intuitions right. Anthropic principle doesn't get involved here in any way. If agriculture was invented 5 times independently it couldn't have possibly be the limiting unlikely step.
2 might be luck - something might have been extremely unlikely but just have happened (by anthropic principle). But anthropic principle doesn't really give any reasons why it should have happened quickly. Of course it's extremely naive to consider (like Robin's paper) time as a series of independent trials - maybe it was unlikely as in prerequisites were just in place, and it was either fast or never. That's why I seriously doubt physics-inspired modeling of such events.
The bias is that we don't even notice things that occured once. How important is there that we have a moon? That we have a continent that spans east-west? That the K-T impact happened exactly when it did?
There could be a hundred other crucial factors which we never even noticed because nobody thought they were important to the development of civilization.
We have a sample of one modern human civilization, but there are some hints on how likely it was to happen.
Major types of hints are:
Data for:
Data against:
To me it looks like life, animals with nervous systems, Upper Paleolithic-style Homo, language, and behavioral modernity were all extremely unlikely events (notice how far ago they are - vaguely ~3.5bln, ~600mln, ~3mln, ~200k or ~600k, ~50k years ago) - except perhaps language and behavioral modernity might have been linked with each other, if language was relatively late (Homo sapiens only) and behavioral modernity more gradual (and its apparent suddenness is an artifact). Once we have behavioral modernity, modern civilization seems almost inevitable. Your interpretation might vary of course, but at least now you have a lot of data to argue for your position, in convenient format.