In travels throughout Latin America, during which I spoke Spanish learned in Spain, local people had no problem understanding my use of vosotros forms even if they lived in very isolated rural areas and had only a few years of schooling. I know that they were familiar with the exact conjugation of vosotros, because they might even repeat back my statement, e.g. “Ayer Usted preguntó ‘¿cómo hacéis esta comida?’, pues, hacemos así…”.
I suppose that in countries with vos or familiar with vos, they assume vosotros works more or less the same. But how does that explain e.g. isolated rancheros in Baja California, in non-vos Mexico, being familiar with vosotros?
For example, has radio in Latin American (since many communities got TV only recently) presented vosotros forms often enough for any child to grow up learning them? If so, in what context would Latin American radio do that?