...the romanticization (and careful sanitization) of the Civil Rights Movement in popular culture led countless imitators to try and replicate its success. Mostly, they got even the most basic details wrong then wondered why they weren't one-tenth as successful: as I eventually tired of explaining to my 1980s peace movement colleagues, what impressed Mr. and Mrs. White America most about Civil Rights kids was how well dressed, calm and polite they all seemed -- these were the kids they imagined Sidney Poitier having; MLK insisted that action participants dress like they would to go to church on Sundays. (A black Pentecostal church in Montgomery in 1964, not that honky Church of Do What You Want you might shuffle into, late, today). You can imagine how that went over with my atheist comrades, whose wardrobes consisted mostly of black t-shirts with stylized yellow fists on the front.
I add that people in their best clothes don't want to pick fights with the police, on expense alone. Likewise, the police won't want the bad PR that comes from a well-dressed protester trying to recover tailoring costs caused by overenthusiastic police action.