A doctor on the other hand starts out making 70k in their residency after 4 years of undergrad and 4 years of med school. Once their residency is over they can expect to make well into the six figures. Probably in the 300-400k range. COVID is a few months of increased danger that happens perhaps once in a career for which some medical professionals are even getting paid extra for.
I don't necessarily think police are under paid but to say you can attract people because of the public service aspect of the job and ignore the vast pay difference seems to ignore the obvious difference.
They get paid a reasonable salary to be trained in a job that will provide them a nice income for the rest of their life. Having a lower salary while in training is not unheard of in any field, I am not sure why you believe those numbers are unacceptable.
Further Baltimore shows why a national $15 min wage is untenable, as all that does is make more jobs "minimum wage jobs" because taking the min wage from $8 to $15 does not magically mean all the jobs that paid $15 now pay $22, that is not how economics work