Right, but in McDonalds case, the parent company isn't the one operating the franchises most of the time, and the franchises are almost always small companies p

Right, but in McDonalds case, the parent company isn't the one operating the franchises most of the time, and the franchises are almost always small companies privately held. So you don't get an accurate look at how the average McDonalds franchise operates. Other businesses have their earnings obscured by different sources of retail, or inexact expense breakdown.