If you really wanted it to be equal cars then you'd have the car makers work together to build one car that is the only car raced in WRC. Then the test would be driver skill. Then again it would take away bragging rights to the racing and the car makers wouldn't want to be part of it. If we want to have a WRC then we're just going to have to live with competition. Besides would we have liked it it Subaru was made to add extra weight or use a larger Legacy because they were doing to good?