The church can take credit too. They called for a day of rest and worship first, but the bumpersticker makers have a point: without organizers the 40 hour workweek would be a reality for even fewer folks than it is now.
Whether you believe it or not, a well known idea about unions is that they help lazy, underperforming people keep jobs, to the detriment of motivated workers, and companies. This month's Vermont Women has an article about the nurses' union at Fletcher Allen. A few people at the hospital express that idea in the article, but when pressed can't cite concrete examples.
All of this is very interesting to a (relatively) new member of the workforce.