

Neither 110VAC or 240VAC is inherently more dangerous as long as the system is paired with the right gauge of wire. As for personal safety, both are more than capable of killing you regardless of amperage. 240VAC may even be a little more capable because it can push more current through the resistance of your body.
I’ll admit, American plugs/outlets leave a lot to be desired, but it’s not any more dangerous because of the higher current.
This is not happening. It is not something that would be possible to hide, there are so many different places this could (and would) be detected by someone with the right know-how (data/battery consumption in particular).
Try and pay attention to how many ads you get that are completely irrelevant to you. It will happen way more often than ones that match up with your conversations.