That's exactly what it is. Fair use is a government granted exception to intellectual protectionism. The government is the one determining what counts as intellectual property violations, and what counts as exempt from punishment.

Without intellectual property law, you would be free to copy anything. The barrier to copying is the government. The free pass to flaunt their rule, when qualified, is also the government.

I fail to see how this situation differs from the distinction between assault and self-defense.

assault and self defense were my analogy of something similar. im saying they are not different in kind. akin to self defense being government sanctioned murder.