I could never imagine an American burning a flag. Even anarchists wouldn't do it
Unfortunately they have and do, which is why we ended up having the Supreme Court ruling after a communist-leaning protestor went down the streets of Dallas vandalizing whatever he could get his hands on, including the flag. His lawyer claimed it was a protected form of speech, and the Supreme Court issued a split ruling, contradicting the laws of 48 states and the District of Columbia at the time which had it listed as a criminal offense.