in my opinion, "taught" seems to imply that siri can actively learn. though siri is an intelligent agent which does speech recognition (firmly planting it in the world of AI), i am under the impression that siri does not actively learn and so saying "taught" in the context of speaking about an AI could be construed as misleading. i could be mistaken about whether siri can do "learning" or not, as i'm not intimately familiar with the tech.