just because there are no airlerons has nothing to do with being a trainer.three of the best trainer designs were 3 channel designs,s-ray,h-ray,kadet.there were others.
So why do airplanes have ailerons? Maybe you are not too particular about learning to fly properly in the U.S. The training programme stipulated by the Canadian national association (M.A.A.C.) stipulates all four functions are mandatory.
Ed S