There is a middle ground though between "employees can't be trusted" and "all is well". It's possible for there to be a genuine difference in affordances such that people are more productive in some places than others. I think many people would be less productive in a dank basement than in a pleasant office, but then again maybe you don't want it to be too cushy or productivity may go down. I don't think it's realistic to expect everyone to be equally productive in all environments.

That said, I share your fear that all such considerations are just a smokescreen. In a larger sense the entire issue of "productivity" is a smokescreen. We don't need "more productivity". What we need is for people to be happy, and potentially that may be achieved by reducing productivity in some ways.