I've wondered the same thing myself. A trainer is a class of airplane exactly the same way 'warbirds' and 'pattern ships' are. just because you CAN train on a quarter scale P51 doesnt mean it is a trainer. Calling a moose a duck doesn't make it quack even if they do both like water. Unfortunatly you are right in that a beginer may not be able to tell a moose from a duck by looking at it and this I am sure has led to the demise of more than one perfectly good sport plane. 'Sport plane' another classification.