Why might one person work more, earn more, and pay more income tax when his or her tax rate is cut, while another person will work less, earn less, and pay less income tax under the same circumstance?

Since the government have to considered how the poor have to sustain their ability to lives.

If the people with high annual earning have to pay 5 % more, they probably should wait for 2 another months to buy a new car.

If the people with low annual earning have to pay 5 % more, they probably have to face food shortage to feed their children the next day