People who would be interested in rioting generally don't show up to riot unless they can be sure there are a lot of other people who will do so as well. A "one-man riot" is just a stupid vandal the police have no trouble arresting. And so communication of intent to riot is not really enough. There's a coordination problem akin to a massive game of chicken that needs to be solved.
Usually, the way this problem is overcome is that rioters show up to peaceful protests and engage in a sort of signalling game to other would-be rioters. The usual trigger to begin the riot is the sound of shattering glass. Until someone is ready to throw that first brick, you aren't likely to see much of anything.
Authoritarian countries know all this and they try very hard to prevent riots by banning all peaceful protests. Much harder to start a riot when there aren't any people on the streets to give cover.
Usually, the way this problem is overcome is that rioters show up to peaceful protests and engage in a sort of signalling game to other would-be rioters. The usual trigger to begin the riot is the sound of shattering glass. Until someone is ready to throw that first brick, you aren't likely to see much of anything.
Authoritarian countries know all this and they try very hard to prevent riots by banning all peaceful protests. Much harder to start a riot when there aren't any people on the streets to give cover.