The problem with these devices is they don't ask for more context, like a human might. Sometimes they use telemetry for context, but most don't seem to keep any memory of previous questions asked.

If Siri asked: did you mean London, Canada or London, England, and then perhaps weighted that response in the future, that would probably end up creating a feedback loop where it would get quite good.

In the case of Siri, Apple has said they are very committed to privacy, and this might preclude this type of solution.