Would they make money if they were stand alone airlines that had to price, market, and manage a product? Probably not.
---------------------------------------------------
Another point. U absorbs the costs incurred by the affiliates. In my station, the only thing Mesa owns is a set of steps; Chautaugua, a coffee pot maker. When they need ground power, ice, deicing, etc., U provides the equipment and personnel. My research indicates NONE of these costs are borne by nor allocated to the affiliate.
Now, in the grand scheme of things, it MAY be cheaper overall for an affiliate to transport the customers. But if an accurate accounting were done, we'd actually KNOW, wouldn't we? IIRC, Piedmont and Allegheny had a devil of a time getting these numbers, if they ever did, during concession talks. Hummmm.