In my eyes they are not fair, because while they tax consumption, they very disproportionately affect buying power the less wealth you have. For a millionaire, paying let’s say 30% more for new shoes is not going to meaningfully change how much money they’re left with. If I’m poor and I need new shoes (because you can’t just afford a new shoes when you want them so it by necessity implies you’re in desperate need of them), that extra 30% means one less grocery trip. Or heck, even 30% on groceries potentially means one less grocery trip.

Which is to say, being poor is expensive, and sales tax only makes it more expensive, while literally not affecting the bottom line of those in higher income brackets.