This was a Critical Mass event, which is why the bicyclists are taking up all of the street as a way to reclaim the streets and protest the lack of safety for riders under usual conditions. It’s not legal, but protests are never useful if they’re fully legal now, are they.
Drivers are the ones who whine to politicians to stop urban planners from doing their jobs properly.
But that’s not true. Drivers aren’t a cohesive group. Just about every adult in this country drives. The people who are against more pedestrian development are either NIMBYs or the car lobby.