I think you are mischaracterizing both the nature of Bayesian probability updates, and also the foundation underlying scientific expertise. In the first case,

I think you are mischaracterizing both the nature of Bayesian probability updates, and also the foundation underlying scientific expertise. In the first case, prior probabilities are more often than not weakly informative. In the latter case, experts usually rely on a huge volume of information, beyond what most laypeople could even imagine.