http://www.usnews.com/education/bes.../10-most-affordable-private-medical-schools/9
4 out of 10 are DO schools
http://www.usnews.com/education/bes...0/10-most-expensive-private-medical-schools-2
0 out of 10 are DO schools
This leads me to believe it has more to do with scholarships and parental contributions than anything else.
Look at this, I know its from 2004 but its the most up to date I could find
http://www.aacom.org/resources/bookstore/Documents/special-report.pdf
It appears that only 30% of osteopathic medical students had a parental combined income of 100,000 (look at pg. 35)
Now look at this...
https://www.aamc.org/download/102338/data/aibvol8no1.pdf
The average family income in 2006 (I know there is a 2 year difference) for MD students was 100,000
These statistics, while maybe not the best (but the best that I could find offhand), may suggest that parents of MD students just make more money and are more able to contribute to their kids education expenses. It may actually have little to do with the tuition that these schools charge.