I like the idea of the rich paying more. Seems fair.
Why punish the rich for being rich? Poor people should pay more taxes as they have shown they are unable to work with money and unable to use it productively for the benefit of the country.
Anyway, if we all payed for products based on a sliding scale there would be no use in earning more money if things just become relatively more expense. Therefore the doctor or engineer who spent hours awake studying will not be motivated to do that anymore - communism. In a country like ours where laziness is a common problem, communism/socialism can not work.