That's how the federal income tax started - a tiny, flat tax.
It was only to start at a person's income of something like $10,000, which, at the time, was enormous! And then the tax was only something like 1%.
It proves that it's better to not trust the government in such things. They love to get a foot in the door and then blow it up into a really obnoxious program.
This one's blown up & obnoxious before even getting out the shute.