Earlier quoted context omitted.
The parent comment talked about a flat percentage tax. So the people with more money would not be paying the "same tax". They would still be paying a lot more. A truly fair tax would have everyone paying the same flat fee for the same public services rendered.
It isn’t, though, because of the marginal utility of money. Someone making $10k/yr sees much more value from an extra $10k than someone making $10M. For one it’s a lifeline and for one a rounding error. While a flat tax is fair in numbers it’s not fair in marginal value or utility. IMO that’s a much bigger deal. There are other macroeconomic advantages to giving the little guy the extra, though I don’t want to repeat…
I understand that goods and services acquired with currency can experience diminishing returns. But unless you think the rich and poor should be paying different amounts for every good and service (for example a cup of coffee), then I don’t think this is a consistent, principled argument.
And once again, let me point out that GP’s comment on a flat tax would STILL mean the rich give up more value than the poor, and it would still not be a truly ‘fair’ tax. And on a side note, ‘progressive’/‘regressive’ are made up terms used to play rhetorical games by leveraging the negative connotation of the term ‘regressive’. A better set of neutral terms would be ‘uniform’ or ‘fair’ or ‘flat’ versus ‘non-uniform’ or ‘unfair’ or ‘graduated’.