To be clear, the apps in question do not turn on shut down phones; they only turn on the WiFi function on an already on phone. As for the question of the unauthorized access to your cell's WiFi, if you install an app that is capable of independent turn on, they almost always tell the user of that ability during the install process and/or in some form of EULA available to the user(s); basically, like a lot of other forms of online consumer offers, you often end up giving up some control in order to get the end "benefit"...
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