I'm not the poster you're responding to, but I suspect (bitterly) that it's because engineers and architects are held liable if their inattentiveness to detail causes someone to die, whereas medical professionals are not unless they do something so wildly negligent that you could prove it led directly to an already sick patient's death. (And even then). In most engineering scenarios, there's a paper trail leading back to every decision, and what you're working on is a determinstic system with known inputs and expected outputs. In the medical field, it seems as if a second opinion is more akin to getting food at a restaurant and then taking it to another restaurant to ask the chef if it's too salty. The inputs are subjective, the results can't definitely be traced to them, and no one expects anyone to live through the meal anyway.