One thing is that the rigid terrific schedule of the modern-day residency program was designed by a cocaine addict who made the structure to fuel and hide his addiction, so all doctors start out with a skewed sense of normal working hours. (https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7828946/)

Another thing is the toxic culture perpetuated for allowing medicos to stroke their egos - toxic cultures about overtime are everywhere, but medical profession is a class apart.