Actually, coöps can work under certain circumstances. Indeed, even relatively pure communism can work in societies that are small enough that everyone knows everyone else, and where people inherently reward hard workers and shun slackers. Unfortunately, such societies are very fragile, and coöps can usually only survive if they both maintain a narrow focus and have a means of accountability (either direct, if they're small enough, or financial, if they're larger).
The few that I have seen here in Massachusetts always lacked strong leadership, the group will not surrender power to a driven task-master. The few that I have seen seem to have faded away. In my mind, they are not stable. Imagine if you can a co-op competing with Bill Gates.
Linda Ellerbee tells a great story about that.
She lived in a commune for a while during her idealistic youth. One day she needed water for the meal she was cooking, so she trudged 200 yards down a step snow-covered hill, at night, freezing her butt off, chipped through the ice over the stream, scooped out a bucket of freezing water, and trudged laboriously 200 yards back up the slippery hill with a heavy bucket of water.
When she got back inside, a guy lying on the couch watching TV glanced over at her panting, frozen visage, lazily said, "far out, man...", then turned back to stare slack-jawed at the TV.
She moved out the next morning and got a job.