Why? Because you're whining and they know it!
...
No, seriously... there is an exact science to it... but it eludes me.
I've found one thing constant: The more I work, the more I get back.
My return rate this year was nice. 1 dollar for every 6.8 I made.
...
The military is kinda nice in this regard: I didn't have to pay taxes for the entire years of 2003 and 2006 due to being in a combat zone.