why can only siri use the english canadian voice

I find the English - Canadian voice on my iPhone the most comfortable one to listen to, however, it is only available on Siri. It is not available at all on OS X Mavericks which you would think would have a larger selection of voices. Why? Surely it would mean less memory for the phone/mac to use the same voice for all?

Why does the dictation on the iPhonehave to take place over the cloud? It is rather tedious having to rely on 3g to work we;l in order to use sms as a visually impaired person. Surely there must be a way for it to be non cloud based? If it means sacrificing a gig or two for it I would rather after all that is why i went for the iphone with the largest memory.

Couple of other questions which I would love an answer to are

1. Why Command + Left Arrow shortcut not work under BVoiceOver?

2. Is there a shortcut key for read the document from the point where the cursor is to then end of the page?

I have tried asking these of the accessibility team at Apple, however, after 4 months of silence I have come to the conclusion that Apple do not actually intend to provide support through that method.

Cheers,

niteblind