Stealing is illegal, as is assault, and you are not convicted of assault in cases of self-defense. Similarly, calling fair use "government sanctioned stealing" is a bit of a stretch.
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.
fair use is an affirmative defense, where you say "yes i stole it, but the government should not protect the content owner from me," similar to "yes i injured them, but it was self defense and they do not deserve compensation."
[1]intellectual property violations are not theft in the strictest sense of the word, they don't remove the original. stealing in this context is colloquial.