There was one of these where I used to live. I don't know much about it though. TBH I think the only reason they had it was because it was an isolated town, with underprivledged? kids who wouldn't have gone to pre school other wise.
As far as I know, it was free, but not too sure there. It was a seperate fenced off building in the school yard, but is more involved with the sctual school, so when it comes time for the kids to start kindy the transition isn't such a huge one.
I grew up in a town not far from there, but there isn't one there & that town wasn't considered isolated. From 30kms North the isolation line started.
It also had a high rate of Aboriginal residents & I think thats mostly the reason for it being there. It was the only pre school in the town. They had a bus too, to make it easier for kids to attend.