You work at Burger King. It’s pay day Friday. Every two weeks, you earn $500. This BK pays in CASH. No withholding! That doesn’t mean you won’t be paying taxes. As you exit the building, there is a small booth where the IRS will look over your Cash, and take what it needs. Luckily, they have a fancy formula so you won’t get screwed more then the other BK Lounge workers. They need $100 from your pay. Now they hand you back your money, all $400 of it.
If this is how we paid taxes in America, there would be a revolt. But lucky for us, our politicians gave themselves the gift of Whithholding. You can learn more about withholding here: http://www.cato.org/pubs/journal/cj14n3-1.html
Pay attention to that pay stub! And make sure your W-4s are in order!