Been that way forever. Ford and Chevy have had favorable rules as long as I can remember. Pro Stock has always been my favorite class, and all one has to do is go back to the 70's to see the absolute sellout to them. Mopar guys were running Dusters and Demons with Hemi's while the Chevy guys were running Vega's, Ford was running Pinto's. The Chevy guys were running 350 small blocks, Ford was running 351, not sure if it was Windsor or Cleveland.
The Chevy guys had to carry, if I remember correctly, 6 pounds per cubic inch, the Ford guys 6.5 pounds per cubic inch, but the Mopars were hit with 7 pounds per cubic inch. Who has the advantage with those numbers?
It's that way in every form of racing.