I assume all tax is regressive since it takes money out of people's pockets.
Then I don't think you understand what the term means.
Don't get me wrong. I really want to help the working poor in America. But you should always weigh what just sounds good vs what the actual effect would be. Especially unintended consequences.
I used to be fans of flat tax and sales tax until I looked deeper into it. You could make it work but it would require complex and aggressive exclusions to keep the tax burden from shift from the wealthy to the poor.
If I am raising a family and barely making it and not really paying income tax because of deduction, and you want to replace that with a 10% tax I can't exclude from and\or raise tax on food I already couldn't afford for my kids. When you are close to the edge 10% is the difference between scraping by and not making it.
If you are Paris Hilton 10% of billion won't be missed. One day a week you might wipe your booty with $100 bills instead of $1000 dollar bills.
Same tax, different burdens.
Regressive.
So you'd need lots of exclusions and thresholds to avoid those things disproportionally pound those already just barely getting by.
Possible, but most people calling for those things don't want to have to admit the complexity.
You know someone is full of baloney if they start the conversation with, "It's EASY! All you got to do is...." or "The solution is simple..." there are no simple solutions, only complex tradoffs. If anyone doesn't realize that, they haven't thought about a problem deeply.