If implemented as I've seen proposals, progressive rates wouldn't be needed.
We would first figure out a number where poor people wouldn't have to pay taxes on purchases. Let's say $20,000. Then we take our tax rate, let's say 25% to make it easy.
So, 25% or $20,000 is $4,000. So on April 15th every year, each adult gets a check for $4,000 to pay for their taxes under $20,000. So a poor person who spends less than $20,000 pays ZERO taxes. The rate would have to be higher for everyone, but the poor would not be railroaded as allegedly happens now.