By reinforced concrete do you mean they build forms and pour the concrete into the forms, or do you mean tilt-up (pour slabs horizontally then lift them to vert

By reinforced concrete do you mean they build forms and pour the concrete into the forms, or do you mean tilt-up (pour slabs horizontally then lift them to vertical to form wall sections) or do you mean reinforced-CMU (build a CMU wall then put rebar and grout through the cores of the completed wall? Pouring into forms is by far the most expensive technique because those forms are costly to build and set up. In the US poured concrete is only used in simple or horizontal structures (like foundations) or where the cost of the formwork can be amortized over a lot of repeated structures, like the floors of a highrise.