But wealthier people tend to consume more. The top 10% of earners account for~50% of consumer spending. It's more like the low income person pays $5 of sales tax on a $50 pair of shoes, and a high income person pays $50 of sales tax on a $500 pair of shoes.
Haven't you read Capital? Marx's core premise which nobody actually working in economics denies is that the nature of wealth is to consolidate in the hands of the few. So while wealthier people may consume more, that does not factor into "fairness" because they are hoarding their wealth, amassing power over others, and using it disproportionately to maximize their pleasure, power, influence, etc at the cost of the suffering of others.
But I take it from your glib comment you'll disagree or deny that.