[ladberg]

The problem is that we don't know if the "conservative probabilities" are actually conservative. There is only a single planet in the Goldilocks zone that we for sure contains or doesn't contain life.

Imagine if someone showed you a rock in the forest with some lichen in weird pattern and asked you for a "conservative estimate" for how many other rocks on Earth had that same pattern. Maybe pattern is common, but maybe it's something incredibly unique that no other rock has. Because you can't ever look at a different rock, there is no reasonable answer.

[SanderNL]

If you ask a layperson, yes sure. Ask a geologist/biologist/whatever. There is order in the chaos. Some things can be said with certain levels of confidence without (direct) evidence. There are patterns you know.

[enkid]

This is actually one of those things experts are very bad at. Experts make good predictions when they have feedback about those predictions. There is no feedback about this kind of prediction, so experts would be very bad.