system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: Why doesn't a flat tax work?

Perhaps this is naive but to me it seems as though a flat income tax rate would be the most "fair" way to handle taxation - everyone pays the same percentage of their earnings.
gpt
Because money doesn't work that way. If someone making 100k a year loses 20% of it to income tax, it's not a big deal; they might have to cut back on some luxuries, but they'll do fine on 80k. If someone making 30k a year loses 20% of it, it's a much bigger deal; the dollar value is only 6k instead of 20k, but 30k is already not really enough to live on comfortably. That 6k could very well be what you need to get health insurance, or buy healthy food, or pay for heating in the winter.