the thing is, human will rebuild better, have better OOP, better income when DR is low, its only ONCE your draft gets to that level that -ve wages even comes close to +income
and THAT is why + income is better than -ve wages
when your draft is 40-45% (post war for example) the human's income will be far far better than the elves -ve wages
in short +income is in affect ALL the time
-ve wages only works when you have a high army