> Except it turns out people don't want their computer buying things for them.

I think this also hits an interesting problem with confidence: if you could trust the service to buy what you’d buy and get a good price you’d probably use it more but it only saves a couple of seconds in the easy case (e.g. Amazon reorders are already easy) and for anything less clear cut people rightly worry about getting a mistake or rip-off. That puts the bar really high because a voice interface sucks for more complex product comparisons and they have a very short window to give a high-quality response before most people give up and use their phone/computer instead. That also constrains the most obvious revenue sources because any kind of pay for placement is going to inspire strong negative reactions.