For schools with a substantial commuter population, do the numbers include a weighted average of commuter and non-commuter costs? Living with parents and commuting, while it does cost non-zero amounts of money, typically costs less than living on one’s own at the school, so living with parents and commuting is commonly used as a cost-saving measure.
The locations of public universities and community colleges relative to where the population lives can affect affordability due to the possibility or not of commuting. Obviously, those who live in sparsely populated areas are less likely to be in commute range of any college, and colleges in sparsely populated areas offer the commuter option to fewer possible students. Also, if the only school in commute range is a highly selective state flagship, nearby students who are not top-end students may have to spend room and board to attend college elsewhere because they could not get into the nearby highly selective state flagship.