Voice is the feature people ask the most careful questions about, so here's the whole story in one place, moved off the pricing page where it was asking shoppers to care about architecture before they cared about the product.
Voice that learns instead of asking every time
Voice commands are not one big call to a language model. Your phone reads the sentence first, checking it against what you have already written, so a shop you have typed before is recognized as that shop rather than as whatever it sounded like. Most everyday commands are finished there and never leave the device.
What your phone cannot place goes to us, and even then it usually costs nothing to answer.
What leaves your phone is stored as a shape
Sentences shaped like ones other people have said are matched against a pool of patterns that holds the shape and not the contents, with the name and the amount stripped out. Sentences you personally have said before are remembered against your account as a shape with the name and the amount taken out, filed under a one-way code rather than the words, so the second time is instant and there is nothing in that store anybody could read back.
Only the awkward ones reach a language model
Only the genuinely awkward ones go to a language model. That is a small share of what people say, and it is the reason the microphone does not have to be priced like an AI product.