Every tax system is. Because the experts who help to develop it are the same people who get paid to help you file your taxes. Making it easier would lose them income.
It is a combinatorial explosion problem. Each taxing authority probably isn't too different from the norm, but in the US you are more likely to encounter many different taxing authorities that overlap.
Come to Brazil, we have taxes on products 'circulating', moving your products between logistic centers is OK, but if the product is lost or stolen, taxes are due (as if it was a sale).
Some tax regulations were considered illegal by higher authorities, but that won't stop a tax auditor in a local level charging them and potentially closing down your business.
