> If you consume the same amount of resources/services I do, and you happen to make more money than me, how come is it "fair" for you to pay more taxes?
Because of the marginal utility of money and the burden of taxation. A 10% tax hurts someone living on the margin far more than someone living with excess and thus the burden is not shared fairly. Taxation of income is more fair than taxation of consumption because the burden is shared more equally. Not the "amount", the "burden".
> Percentage-wise, a consumption-based tax could take more from the "poor and middle class".
Which is what matters.
> In absolute terms, not so much.
Irrelevant, see above.
> Incentives to saving - economically debatable for a government
Not their job.
> Good for the environment. Imagine if China actually had to start paying for things like carbon credits.
Not on topic, this doesn't require consumption taxes.