This thing meant to make life simpler may actually make it more complicated. However, there are the brighter sides of things, like one can find a persons who goes missing by finding out where he or she was at the last time Google accessed the device.

Technically I am sure that you can indeed turn it off as you wish. Unfortunately, the social mores are different. If you let you girlfriend/parent/colleague get used to being able to track you, then the day you turn it off is inevitably the day when that person is specifically going to quizz you on why you turned it off.
Thus turning off the tracking is the very thing that is going to get people suspicious about what you were doing. That is why this is spyware. Not because the app is made for that, but because of the way the app is going to change the lives of the people that use it.

telling someone where to go when they get lost.

Having a girlfriend who tends to ride her horse around on the Northumbrian Moors for unpredictable amounts of time, I could see a definite use for this one - even if it was only to get some idea of when I can expect to see her coming in through the door, streaming brown water all over the place and smelling slightly of compost. For her, this could mean the differnece between cold pizza, burn pizza and just nicely toasty-rich pizza. Mind you, I bet having it running all the time murders your mobile's battery (asuming your mobile's battery hasn't already murdered you, of course - oh, wait: that's a different story).

Why the heck are you calling this a spy app when you can decide on a per person basis whom you want to share your location with. You can even artificially set your location to a false one for a person. You mentioned all this, but why the title?