The steel frame I saw was engineered to accept normal plaster panels, with a brick veneer exterior cladding.
It would not surprise me to learn Lustron went broke, enamelling is a costly process, particularly with large panels.
One thing that could be said for that type of house, the owner never had to worry about termites, borers or mold. Although they could be noisy.
In the US and Canada, I am amazed at how many houses have roofs of timber shingles. Tarred, even. A fire waiting to happen, insurers must not sleep well at night.