I imagine it is a hard shop to fill.
One one hand, you have devout shoppers who may take offense to working on Sunday, attending a church that's not their own, or reporting on the behavior of something that many want to feel is a spiritual experience, and not a business. On the other hand you have agnostics and atheists who may not appreciate what a place of worship has to offer, or feel comfortable being there.
That said, it's probably a valuable service to offer any place of worship that's trying to increase it's numbers. Like all MSing fees, the pay rate simply needs to be sufficient to attract shoppers.
My idea of a Sunday shop is brunch, but I maintain that everyone needs to find their own path with MSing...