I've always wondered, why can't we just pay one tax? Say make income tax 1.5x what it's now and cancel all other taxes. That way it'll be even easier!
Wealthy people are against that. They prefer regressive taxes, like sales tax, that will be shift much more of the burden to the poor. In fact, there's a whole batshit-crazy tax plan called FairTax that proposes changing all taxes to a simple sales tax.
I don't buy that. Yes, I know it seems logical, but in practice it's not so clear cut. With deductions, rich people end up paying very little for income tax. With sales tax (or VAT) the person spending more pays more, and it's more difficult to escape.
This issue is very unintuitive and numbers tend to hide reality. Let me put an example on how numbers can fool us.
In my country, Spain, there has been a recent discussion about what economic model we want. Left wing parties argue that in countries like Denmark (that's seen as a very good place to live) taxes are higher than ours.
But that's terribly misleading. The important number is how much money you're left with after paying taxes and what you can purchase with it. Our salaries are too low so, even if the tax percentage is lower, and prices are a little lower (not in Madrid or touristic areas) we still are poorer after taxes and we have worse public services.
Tourism is poisoned candy.