HO vehicles-am I missing something?

[nachoman]

Probably at one time their products were all metal. They found a cheaper or better way of manufacturing in plastic, and they went with it. But rather than lose brand recognition, they kept the same name. Same can be said for the Model Die Casting brand of trains. At one time, they were all die-cast metal. By the 1980s, they were mostly injection-molded plastic. Or how about the HO scale items sold by the "N-Scale architect"? At least "Mantua Metal Products" shortened their name to just "Mantua".