The author's phone spied on him, determined he was in the same household as his wife who had been searching for a Dremel and then it later showed him an ad for a Dremel. If that isn't spying on you to show ads, then what is it?
I get this is a popular topic ("your phone is listening to show you ads"). And already had some non-technical friends ask me about it. So at least the article gives a detailed explanation about targeted advertising and fingerprinting.