> Depends on the app; I expect, for instance, market apps (Amazon, Walmart, etc.) to watch the user's every move to try and better model the user's mental state

> Depends on the app; I expect, for instance, market apps (Amazon, Walmart, etc.) to watch the user's every move to try and better model the user's mental state in an effort to get them to buy stuff that they wouldn't have done otherwise. Not being funny but I think you’re vastly overestimating the capabilities of most engineering teams.