If this isn’t shut down quickly, I predict we see a national movement like this by Juneteenth.
So the police aren't going to storm the barricades -- they figure they won't have to.
The police let the anarchists do whatever they want, within certain constraints (no injuring people, constrained to certain neighborhoods), and the anarchists only do it on that day of the year. Sometimes there are conflicts between the police and the rioters, but it never escalates to huge conflicts any more.
It’s a display of mutual respect for authority, and it allows the radical groups to blow off some steam, while campaigning for progress.
I know this idea makes no sense to law and order -type people, but it’s an ancient human idea to ritualize and sanctify the behaviors you want to discourage or control.
Your last paragraph reminded me of Eric Gans’ “Originary Hypothesis” [1]:
> Gans hypothesizes that language originates in "an aborted gesture of appropriation," which signifies the desired object as sacred and which memorializes the birth of language, serving as the basis for rituals which recreate the originary event symbolically. The originary sign serves to defer the mimetic violence threatening the group, hence Gans's capsule definition of culture as "the deferral of violence through representation."
[1] https://en.m.wikipedia.org/wiki/Eric_Gans#The_Originary_Hypo...