If you go read the abstract of the study cited, you should note that the mean age of the physicians interviewed was 68. I think hospitals do a lot of unnecessary CPR if the wishes of the patient are not known. If someone expires after a long illness or after a very difficult surgery there is little and less chance that perfunctory CPR will be helpful. There is a lot of difference for a relatively fit person who collapses on a treadmill. The odds are stacked against them but its not nearly so futile.