No one does a "career" just out of being a good person. Not even clergy meet that bar of motivation so there is no need to imply that this is a failing of any doctor. However, if what you more meaningfully are trying to say is that you've never met a physician whose primary passion for doing the job of a physician is a deep and strong interest in providing care to sick people, then, you too need to spend more time understanding folks and talking to them. Start in the global health department or try pediatric infectious disease specialists. A career encompasses many motivations, for more doctors than some might think, providing compassionate and skillful care to help people is one of the key ones.
Sick all the time? I admit that during a pediatric rotation a case or two of kiddy crud is common. Since my residency was completed, I've not had that happen though. Most URIs you'll get come from your own children, even in pediatrics.
Again, no "career" is perfect and it is not a human failing or motivational "fail" to choose careers based on more than "helping people". However, I believe that being a physician is more than just a "job" and after 30+ years of being one, continue to love the job and am grateful to those along the way who encouraged me. And yes, I continue to do 30 hour continuous NICU shifts.
Paying it forward, ya' know...