Building houses with concrete is quite a skilled job involving a lot of labour putting together the custom forms. I suspect in higher wage countries it becomes

Building houses with concrete is quite a skilled job involving a lot of labour putting together the custom forms. I suspect in higher wage countries it becomes more prohibitive as a building method. Certainly it's very rarely used in the UK for residential building. Timber lends itself well to building insulated structures. I guess nothing is stopping people building a bunker if they're worried about building something tornado-resistant and they dont mind spending more.