About 20 years ago here in Australia, the sales tax was simplified. It used to be that you'd pay 0, 11, 22, or 33% tax on goods if they were classed as staples, luxuries, or something in-between. They scrapped this and replaced it with a flat 10% tax nationally, except for staple foods. My mother was a bookseller, which was previously tax-free (so it wasn't good for her business), but she said that other vendors were over the moon at the much greater ease of compliance. If you ran a mixed business, it was a pain to track which items were 11% versus one of the others.

Then I look at the US system and... shudder. Sales taxes can come from several different levels, and then be chargeable depending on where the seller is and also where the buyer is. It's ridiculously complex. But fixing it means that some people will have to pay a little more (never going to happen) and some entities will lose political power to someone further up the chain (also never going to happen).

On the other hand, the US economy is ridiculously powerful, so perhaps they can afford to waste money on process, keeping armies of accountants employed :)