Lawyers understand, that if they have not heard all of your story, their case might crumble. They know that it is the same for the adversary if one is involved in their case. For them, a big part of their communication is about finding the missing information. The time they invest in listening and understanding the situation pays. Their job consists in figuring out all of these details.
For doctors the situation is different, they too can depend on the patient telling them all the relevant details. But there is rarely another doctor involved who will look for the details they missed. Beyond this, it often is less the diagnosis than the care that has to take place after the diagnosis that is relevant for the success of the treatment. However, their time is measured and many struggle to make sure that patients follow the given instructions.
Client and patient tend to trust the authority they hired to help them. They follow what they hear and understand. And as it’s an authority they rarely question what they are being told.
Why should they then act differently in the professional field? They follow the given instructions as long as they think they can make sense of them.