I've been out of residency 2 years. I spent one year as an attending, and one year as a fellow.
In fellowship, my butt was kicked, but IMHO, it's not hazing, but a clear and valid ego-dystonic process of being taught by the best and having to undo some bad habits. E.g. I've had to write reports, and I had to have people point out that medical jargon is not understandable by judge and juries. 8 years of having that hammered into my head, and now I've got to get it hammered back to being able to write like a human being, not a medical doctor.
I think part of problem in medical education is we're going through a culture change where the hazing element is getting some backlash. People have realized that they don't want a doctor who's been up 48 hrs. straight providing them care. ACGME guidelines have been created to provide residents some protection.
This culture change, however, will likely take several more years, if not decades to cross-over. There are still programs that operate in clear violation of the guidelines. Residents are often in a position where they do not want to contest violations because they believe the program will be able to narrow down who was the whistle-blower. Despite the guidelines, there are still programs that intentionally foster a "malignant" atmosphere and want to keep residents in fear.
Aside from that, another problem is several medical doctors aren't good teachers, yet the very supply/demand dynamics of the profession pushes several doctors into teaching positions who can't teach. Several programs have problems finding a doctor to take a position period. So if it's a teaching position, the hospital will likely not care much about the quality of the teaching so long as the floors are attended. I've even seen hospitals willing to keep bad doctors who aren't even attending to the floors. When these doctors mess up, the hospital takes it out on the floor staff because they're more expendable, or even the residents.
I've also seen several attendings in teaching programs state they're doing in it on the full expectation of wanting an easy job where they could've made the residents do their dirty work. While I was a chief resident, the attendings that didn't do as much teaching, I didn't put residents on call with them when I had the opportunity (the number of resident calls available could not fill all the call requirements leaving a few nights/month with only an attending on call). I figured-it should be a merit system. If an attending is actually teaching, then that attending should have a resident. If not, then they don't get one. Apparently, I was the only chief who thought of this and implemented it in years. I had an attending come up to me in anger demanding I give him residents (and it's the same one I mentioned later on below). I told him that the call schedule was worked out and approved by the dept. head and I, so if he had a problem, he had to go to the dept. head. Leave me out of it, and that dept. head was well aware that he was not teaching. Checkmate. He knew he couldn't complain to her without revealing why he really wanted a resident, so he let it be though he was ticked with me.
Aside from the doctors, ironically the good doctors also can cause this problem. I'm not talking about doctors that are good because they can teach. I'm talking doctors that are phenomenal in research, but they are poor teachers. Some of them view teaching as a chore. I've had that problem for years in college. Several of my professors openly stated in class that they hated teaching, and if we didn't like their piss poor performance, too bad--drop out of the class. Problem at Rutgers is several of these classes were required for our major and there were no alternatives. Another problem was that by the time you figure out the class was bad, you were trapped. You can't (or at least when I was there you couldn't) drop a class after two weeks. Compare that to several other schools where you can drop out of a class up until (sometimes even with) the final exam. These professors brought in research dollars, so the fact that they didn't produce happy students was menial in the eyes of the administration. (And let me make this clear, I, like many of you are full aware that our best teachers didn't make things easy on us. They challenged us, but they also cared about the quality of their teaching. They didn't make things hard for the sake of hard. They did it for us to learn. A teacher that actually makes a tough but good teaching experience is likely putting a lot more work and effort into his teaching than a bad teacher who makes things tough on a resident because he's lazy.).
Intellectual narcissism is also an element. I've seen several doctors who may be performing better, or scoring better, what have you, enjoy that, and allow it to be a self-indicator of superiority. I've seen this phenomenon dramatically increase in some institutions with a rep for having on average students and residents with higher scores, (although I've also seen several good institutions where this is not the case). I know at least a few doctors where I asked them a question because I wanted to learn, and the doctor, not knowing the answer blew up in anger. Hmm, maybe they just could've done what I thought the best PD I ever had did. Just say you don't know, and then mention that all of us have to figure out what the answer is before the next time we meet.
As for medical doctors, several of them don't want to go through the process of learning to be a good teacher. IMHO a lot of this is due to the medical culture that puts doctors at the top. IMHO, a valid method is for residents to score the performance of their attendings. I've seen attendings in meetings blow up in anger when they got less than stellar reviews from residents on their teaching. While I was a chief resident, I talked to an attending about the residents' complaints and he said something to the effect that he earned the right to spend less than an hour a day at work, while the residents did everything, and all he wanted to do was sign their notes without even reviewing them with the resident. He mentioned that being an attending was an honor, and that he earned it, and in what I interpreted as his attempt to dampen my concern over this issue, mentioned that I was about to earn this same honor in a few months as if we were colleagues.
(Hmm, well needless to say I was ticked off with this guy. I was even more ticked off that he did this for several several months before anything really happened, but at least at the end of my year, a new department head was hired who told this attending to either do his job or he would be fired. Some people in the program told me later on they had reason to believe he was double dipping--working at two places at once during the same hours.)
(Overall, I thought I was in a great program. Despite I wrote above--which really did happen, I've seen these types of things happen everywhere. The problem IMHO is not that these things happen, but the program's response. Just like a residency program will most likely get a bad resident over a period of time, same goes with attendings. That does not make a program bad. It's a lack of response or a bad response that is bad.)
Bottom line is our education needs to be tough, but IMHO, the education chain is full of conflicts of interest and excessive hazing. To be honest, I actually do think there is some benefit to someone having worked 48 hours straight and some other tough elements of residency. IMHO utilizing a preplanned, occasional fartlek (and yes, that is a real world) to make residents a little tougher is not a bad thing (but with that, the resident should be allowed an extra day off, and a ride home provided by someone else). Problem with that is when it's allowed, several hospitals will push it for the wrong reasons--cheap labor, and lazy attendings.