Hi Yvonne

I don't know about it being correct that residencia is needed to get free prescriptions and health care, but we did have to show our application for residencia when we went to INSS to register our froms from England.  I also understand that there are occasions when you might have to provide ID and proof of your Spanish address eg traffic police, and the residencia card serves this purpose, which your passport would not do.  It is also a f*g having to carry your passport all the time in order to provide ID when required, as not everyone is happy to accept your driving licence as proof.

Tony