Call me naive (or perhaps paranoid) but I've been assuming my location is being tracked since I bought my first smart phone years ago.
Here's a way that is tracked. Every 12 hours, your iPhone sends its location. Just that, not personal info. There's an iPhone here in Glendale, CA. About say, 12,000 of them. From other databases, advertisers know the demographics, salary data and so on for that zip code. This determines who the ad might be shown to. Will everyone in Glendale be sent a particular ad? Or do you want to send the ads to Beverly Hills?
Seems okay with me. In the Terms of Service, that's what they say. Every time you ask for GPS, it tells you and you have to click. Every time, not just the first time you use the app. That's exact info. Things like Yelp! use it, and they're compiling data about the iPhone users in 91202. And sell the numbers to advertisers. Apple doesn't see that, either.
Don't like that? Try a magazine subscription. The magazine sells your name, address and other subscription data to advertisers. A lot MORE than an iPhone gives. So you find all kinds of crap, for years, showing up in your mailbox, and you can thank the publishers. Oh, by the way, 30% that Apple charges is a better deal than most distributors give. Why are some fighting that deal? Because Apple won't let them collect your data for their use.