In medicine you want the doctor who's willing to admit "we don't understand the exact mechanism here" + also who wants more details from you before making a decision, vs confidently brushing you off and writing a prescription as fast as possible.

Lawyers will usually give much less-certain answers to questions like "is it legal to do X" than lay people as well because they're aware of much more nuance in the law. (Not referring to the wishy-washy corporate-law answers given to avoid liability here, but in outside convo about issues.)