I am also puzzled. Apple's iMessage/SMS app (there is only one app that does both as you say) will only send iMessage messages to numbers that have iMessage ena

I am also puzzled. Apple's iMessage/SMS app (there is only one app that does both as you say) will only send iMessage messages to numbers that have iMessage enabled (I know there are some edge cases but these are typically only for those who have recently migrated away from Apple). iMessage will always default to SMS (and is usually the only option) for numbers that have no iMessage enabled. Not an Apple fanboy but how they have set up iMessage/SMS actually is pretty good.