Under a 20% “flat tax” scheme, someone making $10,000/year pays $2,000 tax while someone making $100,000/year pays $20,000 tax, i.e. $18,000 more tax. It’s somehow OK for the richer person to pay $18,000 more in taxes than the poorer person just because he or she makes more money, but having that person pay $18,001, $19,000, or $25,000 more in tax would…