You misrepresented the arrangement. They didn't just cut you lose in the ER after med school, many of my friends and family are MD/DO's of one description or another, I know how it works.

Consider the time building phase (1500 hours) as med school rotations.

Consider the first few years at a regional (including upgrade) as residency/internship.

Maybe your board cert is major legacy airline interview/ new-hire checkouts.

Any field requiring judgement in circumstances where the right answer cannot be found cut-and-dried in a book (essentially all "professional" fields) is going to need some sort of OJT beyond academics to develop that judgement.