Having done some UI work on the front end of voice search this analysis doesn’t surprise me and confirms Siri is not all that different under the hood. (The natural language of Siri is their secret sauce.)
Voice search is a tricky animal, but if you can get the user to narrow a search into a category (called a “vocabulary”) then you can get very accurate results.
This is why Microsoft’s Ford Sync has users start with “play artist”. The user is identifying the vocabulary as music/artists and reduces the possible results to hundreds from tens of thousands.
It’s quite easy — and therefore tempting — to repurpose a web site for mobile by simply building an iOS or Android native app “shell” that merely loads a web site. It’s a recipe for instant app presence: publish this month, not next quarter.