I (and I assume this is probably true for most people) don't want you to have access to this kind of information about me. It's as if you'd want to know every book on my bookshelf. I'm not letting strangers into my home to get that information.
So is one's location while in public. It doesn't mean I want someone tracking my location every time I leave the house. The aggregation of public data can end up being an invasion of perceived privacy.