I think the rationale here is that the intensified production in greenhouses frees up formerly used as agricultural land elsewhere that could then be repurposed

I think the rationale here is that the intensified production in greenhouses frees up formerly used as agricultural land elsewhere that could then be repurposed for wildlife and insects. Personally I am not sure this math adds up. At least in Germany farming land is categorized and once the land loses its status as farmland, it can never be turned back into farmland, losing much of its monetary value in the process. Thus the land owners have an intrinsic motivation to keep their property in the farmland category.