The idea of field hospital is to move non covid related patients to the file hospitals and let the regular hospital to be covid only. This way there is much smaller chance to get covid while getting routine medical care. Reliable source told me medical facility utilization rates aredown more than 50% in non covid hot spot area. People are simply deferring non emergency medical service. They are also not so sure if they need to quarantine non symptomatic covid case away from home, like china did. So the field hospitals are built as an option if needed.