Your math is disingenuous. 10,000 SIM = 10 x 1,000 SIM. 5 MIC = 2.5 * 2 MIC -- you are scaling by a different amount! Give me the numbers for a 10,000 SIM city with 20 MICs vs 1,000 and 2 MICs.
Also, your perspective is skewed. 1,000 SIM / day income is not a small city! That is 50x my current size!!
Then you only need 1 MIC and you will earn way more from it than you would pay in the taxes to support it.
And like the example I gave you with ECO, it's impossible for all the top players to fully offset their taxes by buying enough MIC. (While MIC distributes 80% of taxes collected, while ECO only distributes 25% of taxes collected, MIC is much more rare than solar and wind turbines. I would have to model the precise calculation to find out how far down the rankings the total MIC in existence could cover.)