Taking down a list of people who dined at a restaurant during a certain time period is one thing.
How are you supposed to contact trace a 10,000 person protest? No one is going to know the random people they happened to be standing next to and chanting at a specific moment.
If these protests are super spreading events it blows a huge hole in any attempt at contact tracing & targeted quarantine/isolation. Hopefully it turns out the virus somehow can’t spread well in these conditions otherwise this is a huge setback for a country that just sacrificed so much to reduce the virus prevalence.
Consider that when people are yelling and standing tightly packed together, even if there's wind it won't blow away the droplets, just the aerosols. And new aerosols will be continuously generated...