It really depends. For example, say you are a CA resident, a business major, and were rejected from the state’s 2 flagships (UCLA/UCB) but accepted to UC Davis which only has a Managerial Econ major not Business. However you were accepted OOS to University of Washington directly into the Foster school of business and received the maximum Purple & Gold scholarships. COA at UCD is approx 135k and UW 165K (w/ P&G scholly). The parents have already saved enough to cover both colleges costs and will not have to take out loans.
I could see a family choosing the OOS route in this scenario.