Hi Meg: In the case of marital status, I can say that it's only a fact of the use of the zone where Spanish is spoken. I'm Peruvian but now I live in Spain. Here in Spain, people use "están" but in Perú, for example (and I think in other countries where they speak Spanish too) they use "son". I think that in this particular case it's not a fact of different points of view about if people see the marital status as an state that can change or not, it's only the use in each zone. But this is the reason that I can give you as a teacher of Spanish that see variation of uses in the countries that speak Spanish, it's not an explanation based only on semantics or grammar.