Laweekly: The charged-up crowd of baby-faced 20-somethings, gray-haired activists and a few parents comes marching through the streets of downtown Los Angeles and into the tree-lined plaza next to City Hall on a bright Sunday afternoon. Drums banging, fists flying, people chant, “No on 23!” Actress Ellen Page (Juno) even shows up to throw in her two cents on why Proposition 23 should be defeated, standing solemnly at a podium and telling people that it’s “absolutely illogical to not have a sustainable future,…