It may not be obvious, but its there (or should be). A pilot -- even a private pilot -- cannot recieve a medical cert if he suffers from a serious mental disorder. Items such as depression, bipolar, PTSD, and simular will ground you for life (note, by going through the FAA Medical Officer people with depression are often granted a waiver after treatment).

The physician that signs that cert is testifying to the FAA that there are no mental health issues. If he chooses to not perform formal screening, that's his option. However, for most cases 4-5 questions will pick up 95% of mental health issues, thus they usually do it in a non-threatening way (or where its not even noticed).

The issue with medical personnel wasn't so much what they can or can't perform at 30,000 feet, but rather if they even have the knowledge to attempt it. A true dedication to passenger saftey would have a physician on the ground to direct in flight emergencies (same as an ER doc at the hospital), create response protocols for various issues, standing orders, etc. As I haven't yet seen airlines or the AFA push for this, I assume its not important to them.

Yes, AED's are a good option; however, in over 65 years of combined medical practice at one rural location I am familiar with, there has only been 1 case where an AED would have been useful -- and even then it was questionable. Much more useful would be a stock of drugs like epinepherine, heprin, lidocaine, morphine, etc. A BP cuff would also be useful (but may already be on the planes).