If memory serves me right, the "tweaks" were orchestrated by Uncle Ted after the very possibility under the original ANCSA Corporation formations looked like they would be sold, through stock sales, to non-natives.  After many of the corporations almost went bankrupt and the  stock could be sold to non-natives by the individual stockholders, Ted used his power to stop it with amendments to ANCSA.  Adding on minority preference for government contracts made the corporations solvent again and stopped the possible sale of the stock.  The class structure remains in the corporate have and have-nots system identical to the rest of most of the national economy.  Those below managerial level are left to fight over the trickle-down remains.