I don't think they should be free... I mean it's an operation that a city needs to setup rather than an automatic derivative effect. Collection stations should be built with production like any other building. That said, it seems odd that one landfill would serve the entire nation. I'd rather see 1 landfill allow say, 3 (then scaled by mapsize) collection stations, potentially including one that can go in the same city which would cut down on the actual impact of the landfill. Whether players need to build them or not is a matter of game balance factors to play about with at that stage of the game we haven't spent much time focusing deep on balance issues.