The qualifications required to even enter a medical training program exceed anything required by even the strictest teacher preparation program. It has been repeatedly noted that the standards to enter and successfully complete a teaching pre-service program at virtually any of the nation's 1200 teacher education programs are the easiest of any collegiate professional degree program. The 1200 teacher education programs not only vastly exceed the number of nation's pre-med programs, they vary widely in their enrollments with some so small that it is essentially impossible to have a quality program. By the way, if you wonder why there is such a proliferation of collegiate teacher education programs it has little or nothing to do with the institution's need to prepare teachers. Rather, it is because the colleges make a profit on them.
Most institutions charge a standard tuition regardless of the program a student enters.
An education program requires no expensive equipment, small classes, or any of the other factors that result in an expensive program. For the most part all it requires is someone at the front of the class doing talking most of the time, plus some time spent as a student teacher. Thus much of the money prospective teachers pay in tuition can be used by the institution to underwrite other programs or even non-educational costs. Beyond the technicalities, however, there are other significant reasons why teachers aren't paid like doctors, and they never will be. One is the weight of numbers.