Even if it works exactly like that, let’s say you are poor and barely make enough to live, you still have to give 20% (as an example) to the government, even if you are fucked after and can’t pay rent or buy food. If you make 20% more than you need, you end up with nothing left after. Rich people may end up paying more, sure, but a flat tax still screws over the poor as a rule unless there is some provision that it only starts after X income, and you know that threshold will always be set too low.
Even if it works exactly like that, let’s say you are poor and barely make enough to live, you still have to give 20% (as an example) to the government, even if you are fucked after and can’t pay rent or buy food. If you make 20% more than you need, you end up with nothing left after. Rich people may end up paying more, sure, but a flat tax still screws over the poor as a rule unless there is some provision that it only starts after X income, and you know that threshold will always be set too low.