Just wanted to comment on some things that may affect why the doctors behave the way they do:
1. Liability / litigation. As @timbervest described in post #37, being sued is costly both in financial terms and emotional terms to a doctor. Most doctors are trying their best. Being sued could result in financial ruin. A trial can last months and involve lawyers, the patient, the public, and possibly others reviewing with 20/20 hindsight and with plenty of time and effort events that perhaps were more nuanced or time-critical or were more uncertain when they occurred. During the trial, if it gets that far, the doctor has to decrease their workload (thus lost income) in order to participate.
2. Do everything you can to save me/Grandma/Grandpa/my spouse. In the US, we tend to want to do everything possible. We are biased towards action in medical care. Few of us are comfortable with "Go home and do home care; medicine or intervention will not do much for your illness.", "Hospice might be a smarter move.", "Well, there is a longshot treatment, but the chances of it working in your case are, well, a longshot. And there are side effects, huge costs, dashed hopes, and hassle." Most of us want the doctor to just fix it. Most of us don't want to just give up and enjoy the rest of our (unfairly shortened) life. Most of us think that we're the longshot and will beat the odds, however overwhelming. Atul Gawande's "Being Mortal" book covers this aspect well I think.
3. Doctors are very hurried in our current medical system, especially GPs. For a typical patient, the doctor has maybe 15 minutes to do your examination, address your concerns, update your charts, call in your prescriptions, bill your insurance, maybe draw your blood and/or collect a urine sample, check to make sure you're up on your vaccines, and possibly more. Although they're usually smart people who would perhaps enjoy a discussion of the nuances of PSA testing, they are economically penalized for doing so. And for every smart one of us who are knowledgeable about the subject and just have a quick question, there are 10 people who want to argue with the doctor or have a beef about vaccines, or want to have a very long conversation about their diverticulosis to no benefit, or something. So doctors are wary of long conversations based on the odds.
There are a wide variety of doctors out there, and it is good to find ones that you work well with. Most doctors I know will not take it personally at all if you prefer another one for personality reasons or treatment approach reasons.
I try to be knowledgeable and participatory, but I also try to keep my questions precise, relevant, and important.