Londoners Came to Protest, Americans Came to Chant

I'm beginning to wonder what Londoners will do next to further antagonize city officials. An art instillation made from thousands of CCTV stills form an image of the current British PM Gordon Brown. It's all very V for Vendetta-like (only without the neo-nazi government chasing after the lone anarchist). But this is the kind of existential battle that Camus wrote about in The Rebel. There is always that tension between absolute freedom and absolute justice. Either extreme becomes the snake eating his own tail.
My question is, why haven't American artists started taking this route? I know most major cities haven't gone as far as London in employing CCTVs but some cities like New York and Boston have. Art instillations such at this one are the kind of protest art that I look for. It's not some sweet hippie-styled march, it's the real deal. Protest in America needs to see London's idea of protest and emulate it.