Never say never.
If Justin Bieber or the Rolling Stones suddenly decided to stage an impromptu concert in a public place somewhere in America without a permit, would the authorities ignore it and shrug it off? Doubtful. Even buskers performing in the New York City subway system can't play without formal authorization from the city.
Al Qaeda Operative Who Nearly Bombed UK Shopping Mall, NYC Subway Sentenced to 40 Years in Prison | Katie Pavlich