You can. There's an option on the Siri response to edit both your request and the words you used in the request.

Because the user is normally as unreliable as the machine model.

I suspect that when you are dictating, and you correct a blue squiggle, it raises a flag and sends that back as a failed event.

It also makes me think about the predictive text, does that call back home as well?

Well... the best way to predict text messages is to read lots and lots of text messages.

The difference is that predicting the next word in a text message can be validated without direct human intervention. It takes a human to tell whether Siri interpreted the voice command correctly. It just takes more data to evaluate next-word predictive systems.