Those were just an idea to illustrate the coverage with D12. Of course its just something made up in 30 seconds to get an idea. The differences in cost presumably would be taken care of by addressing the nations favored units with cheaper costs and combining that with added combat values:
so say Soviets will have cheap infantry, cheap tanks, good values for tanks
Japan would have lame tanks, but most likely the infantry would be at 2/2, fighters batter attack, some warships better attack, weak bombers
Germany: cheap subs, better tanks higher price, more costly transports, fighters good etc…
So essentially you create more peaks and valleys in values and costs in order to address the unique differences between each nation so the player will make more historical and realistic buying decisions. When everything and everybody is exactly the same its kinda like a colorless abstract “riskish” type of game.