People are worried because they don't want to be spied on. They also wouldn't want for this information to be leaked somehow in a similar case to when PS3's server data was compensated by hackers. They don't like the idea that they are being watched. The way you explained it is like playing a joke on your friend, and only telling him about it towards the end after all harms done. If I switched your socks and told you I dipped them in dog piss, I'm pretty sure you would then be mad knowing you have been wearing Dog piss infested socks for the longest while.