If some rightwing KKK group had a demonstration, and a small fringe group broke off and vandalized Jewish synagogues and black businesses. I make a bet that will be their last demonstration. They will be banned from any future city and demonized by the press. Leftwing groups can repeat the same tactics over and over and over........ No one can ban them because they are never held responsible for the actions of their fringe groups.
Another thing that protects them is the fact that almost always, their targets are either government offices or corporate outlets. Most people figure the State can take care of itself. And places like Starbucks are huge, non-local concerns, which can easily write off losses.
If they hit small and/or locally-based businesses, it would be a completely different matter. Then again, they're generally smart enough not to do that.