For true fairness there needs to be a single organization nationally that can collect and process the tax. 50 different filings is an unduly onerous and inefficient hurdle for setting up shop.
They calculate and file your returns for you. They get paid a commission directly by the states for facilitating it, so they're free to businesses.
From an outsiders perspective what the USA needs is a proper reform of the constitution and remove a lot of thinkgs from the perview of the individual states.
A maximum age for senators, congessmen and judges would also be a good thing.