Sales taxes are regressive taxes. It's stealing out of the pockets of people who are too poor to find time for politics or who are too uneducated to understand that they are being mugged.
If I was an economist with a college degree, I would also support sales tax.
The problem with income tax is that it encourages the richest to run scams where the ROI is "cost of accountant + tax saved < expected tax = do it". If your income exceeds $100,000, it is almost guaranteed to be worth it to hire expensive lawyers.
Then there are the terrible scams like the one I read (which I can't confirm) where startup founders with public companies receive a minimal income, like $1 per year, and instead borrow their yearly requirements against the value of their shares. That could be $10M tax free - it is borrowing so it isn't income - and a sales tax starts to look like a pretty good idea! That'd be $1M in tax on a sales tax of 10%, vs $0.
Anyway, like I said, tax is complicated!
Sales tax is easy to avoid, especially for the rich: buy things outside of the taxing jurisdiction.