Flat tax systems sound good in theory, but they don't address the problem, which is what counts as income.

Flat $100 per month per person. It's like UBI except it's tax.

Yeah, I think we need to flatten them a different way: tax corporations and individuals on a percentage of revenue (income) they earn.

Then it becomes very expensive to create a shell company to launder money through and games like paying oneself through a corporation lose their appeal.

It also becomes impossible to make low margin products, which would pretty much wreck the economy.

This has been promoted with significant traction many times. But remind yourself who is charged with writing the bills that become laws. Congress, which is funded by wealthy businesses and individuals, makes laws which specifically allow their "clients" to avoid taxes.

One obstacle is the current system has diffuse costs but concentrated benefits. A much simpler tax system would be one in which many accountants would no longer be needed. They're enjoying the concentrated benefits and thus their incentive to protect the status quo is much higher than the incentive of everyone else to change it. They're also facing a loss, which people generally perceive as a more intense event than a gain of the same magnitude.

I think a flat tax as unfair as it is can be fairer than negative tiered as it is today.