Progressive taxation is the most efficient and fair system of taxation. America was it's most prosperous when the top federal income tax topped 90%, 1944-1963. Modern wealth consolidation makes this structure even more logical.
Classically the ranking is :
Least distortionary
Land value taxes / recurrent tax on pure land rents
Broad recurrent property taxes
Broad consumption taxes (uniform VAT / sales tax)
Tariffs / trade taxes
Personal income / labor income taxes
Corporate income taxes
Transaction taxes
Most distortionaryEven if it is, and even if your point is true, that's not what the GP said. They said taxing rich people a higher percentage than poor people is "more efficient" (whatever that means in this context) and a "[more] fair system," and immediately followed it up with the 90% anachronism.