how does a codeshare work exactly (under the surface)
for an AA codeshare on JAL, how does the codesharing work? Does AA pay JAL a set fee for each seat they sell? Does AA keep all the gross revenue they sell on the flight? Does AA contribute at all towards the costs of the flight? So if AA completely sells out the flight, does AA keep all the money and just pay JAL the set fees for each seat and leave the expenses to JAL? Since elite bonus applies for the AA code but not for the JAL code, is it because AA is free to set the fare at whatever it wants? Does JAL only allocate a set amount of seats for AA to sell?
How is this all different from star alliance codeshares? I know a UA codeshare on Air China accrues miles according to Air China's rules and doesn't earn elite bonus, so is the arrangement in Star Alliance different?