As far as the SWA/ATA codeshare goes, SWA takes and keeps the revenue for all the pax that ride SWA planes, and ATA keeps all the revenue from their segments.
The theory is that the combination creates more traffic for each carrier that they originally wouldn't have had. There is no control of ATA by SWA. There are also no overlapping segments except for one obscure one that only lasted a few weeks before ATA pulled out of it. It isn't a scope issue, it is a code share issue, but certainly something to keep a watchful eye on.