> 
> This business of framing an event as a gain or loss has applications
>  beyond settlement negotiations, of course. And sometimes the framing
>  is simply a matter of words—the “cash discount” that is more attractive
>  to customers than a penalty for using a credit card, though they are the
>  same thing; or, to take a legal example, the difference between a tax exemption
>  for doing something or some sort of or penalty for not doing
>  it: again these may be the same, yet they can provoke quite different
>  reactions among taxpayers.
> 
> 
> 

Source: p 228, The Legal Analyst, Ward Farnsworth

Would someone please explain the subtlety? A cash discount and tax exemption is a gain for me, while a credit card and tax penalties are losses? How are they equal?