A large UBI would address this OK, but FairTax seems to really work to keep the tax as regressive as possible without being quite so bad as a flat VAT. A "welfare payment" for "low-income earners" means you have to be in the system ("earner"), that income still has to be calculated, and that the payment is stigmatized ("welfare") instead of presented as an entitlement.

This also seems bad: "The proposed Fair Tax Act would apply a tax, once, at the point of purchase on all new goods and services for personal consumption" - "personal consumption" is arbitrary. A VAT tax applied everywhere for all goods would be fair and harder to avoid. Though even that seems like it would encourage financialization to hide material production.