In the US, the AMA has always artificially limited the supply of MDs. Over the last century osteopathic medical schools basically adopted all the same philosophies of evidence based medicine as “regular” medical schools, maybe with a vestigial course or two on spinal alignment. Both have the same licensing requirements.

At this point, DOs in the US are basically just regular doctors with lower MCAT scores and undergraduate GPAs, and indeed, they basically fill the role of providing doctors to less lucrative specialties and regions.