What is the fine-grained topic of the following text: Also, ignoring the whole parenting thing and legal thing, there is the fact that "spying" or being able to observe them with out them noticing would be nearly impossible, as it would be very apparent that your phone was doing a lot of extra work, as performance and battery life would both suffer when trying to transmit all that information non stop. Only return the topic.
Challenges and implications of spying using a phone