I'm not even going to go into why this is a dumb idea, and how it doesn't take into account the ability for states to regulate their own tax codes.
This has been talked about and tried to some extent in the US, but you can't make it work unless all states agree to a common tax rate, which will never happen. It precludes any ability for states to regulate their own resources as well, and hands a slate of power to the tax board regulating these things in various ways. Go back and read what jillions of economists have already said on this.
We need a federal tax system reform that stops corporations and wealthy people from cheating and not paying taxes. That's what we need.
Well a flat % tax wouldn't be too bad. But that's never what they mean. They want trillionaires to pay the same dollar amount in taxes as someone in poverty. And even if we could get them to pay the same percentage of their income in taxes as someone in poverty. The wealthy are experts at hiding their income.
Though honestly thieves like the wealthy need to be taxed harder than anyone else as punishment for their theft.
A flat percentage-based tax rate would cause a lot more problems than you'd think. Fixing the loopholes to ensure the wealthy are paying their fair share would be of a much larger benefit to everyone immediately. Maybe they can work on the rest of the simplicity after we can stop all the rich bitches from cheating the existing system.
Oh no I get that that's why I said they're experts at hiding their income. All those loopholes would ultimately make it less functional. It would still be more fair than paying the same dollar amount but you're not wrong they will cheat every way possible in order to steal a few dollars more.