> How are smartphones and tablets different from laptops and regular phones in this regard?

Smartphone location tracking data is extremely high-dimensional and sensitive. It is capable of revealing a lot of things which you might not even want to tell to your family. I think for a company such as Google, getting a list of CEOS in e.g. The Netherlands which visit psychotherapists, or occasionally spend the night at the home of their secretary when their wife is on business travel, is little more than an elaborate database query.