This is Switzerland, where land is not as plentiful as in Texas, not by a long shot.
Plus, the support structure is free in this case, it's definitely cheaper to lay solar panels on those dishes than tearing them down just to lay panels on the floor. Also, having solar panels laying flat on ground level sounds like skimming on infrastructure to save money short term but having to pay higher maintenance long term: you have to keep the panels relatively clean for them to work, having them slanted and elevated a bit means that less dirt get on top of them and rain washes most of it regularly.
Plus, the support structure is free in this case, it's definitely cheaper to lay solar panels on those dishes than tearing them down just to lay panels on the floor. Also, having solar panels laying flat on ground level sounds like skimming on infrastructure to save money short term but having to pay higher maintenance long term: you have to keep the panels relatively clean for them to work, having them slanted and elevated a bit means that less dirt get on top of them and rain washes most of it regularly.