No, the fault really does lie with the overly-litigious culture of the US.
Did you know that if you graduate from med school in Canada, they advise you not to step forward if you're on a US flight and someone asks if there's a doctor on the plane?
I'd be interested to see such a citation as well. Quick searching shows that the US (and other countries such as Canada and the UK) have Good Samaritan laws that protect doctors assisting people in such situations. Specifically:
"The Aviation Medical Assistance Act of 1998 ensures that if you're flying in the United States, even if the airline is not owned by a U.S. company, you have Good Samaritan protection."[1]
I also found one article interviewing a doctor who answered the call who mentioned that no physician has been successfully sued for assisting in an inflight medical emergency.[2] A claim that he actually backs up with a citation.[3]
Did you know that if you graduate from med school in Canada, they advise you not to step forward if you're on a US flight and someone asks if there's a doctor on the plane?
Because you'll get sued.