They need galvanized and paint. Something that robots do to millions of cars every year on production lines around the world. Something the robots could do to prefab container structures and cladding prior to assembly, if they were churned out on a production line.
Wood rots. Brick and mortar needs re-pointed. Everything needs maintenance. The point is, cheap affordable housing does not come from currently existing materials and currently existing building practices and techniques.
Prefabricated houses have existed in the UK since the early 1900s when we needed to re-home large parts of the nation after the slum clearances and after the Blitz and other bombing raids during the second world war. Same for many European cities.
Today, prefab houses are a similar price to traditionally built homes because of low production numbers and bespoke high end finishes. When churned out in bulk and to one standard, such as for student or social housing, they're much much cheaper to produce, maintain and replace than any brick and mortar, permanent structure. It's already been proven in Europe.
If you can put together a container home production line to address the housing crisis, it will be the cheapest means of house construction we've seen since building with wattle and daub and as revolutionary as when Ford moved automotive production from bespoke coach built, to the production line.