One of the bigger stories from Mike Isaac's Travis Kalanick profile had nothing to do with Uber at all. The relevant text:

With Mr. Kalanick setting the tone at Uber, employees acted to ensure the ride-hailing service would win no matter what. They spent much of their energy one-upping rivals like Lyft. Uber devoted teams to so-called competitive intelligence, purchasing data from an analytics service called Slice Intelligence. Using an email digest service it owns named Unroll.me, Slice collected its customers’ emailed Lyft receipts from their inboxes and sold the anonymized data to Uber. Uber used the data as a proxy for the health of Lyft’s business. (Lyft, too, operates a competitive intelligence team.)

Reactions to this have ranged wildly, from the paranoiac to the flatly cynical:

But the classic "if you're not paying for it, you're the product" refrain is a bit wrong in this instance. There are plenty of products in the freemium universe that do not sell your personal information directly to the highest bidder. There are also many different ways that products can monetize user data, each at a different point along the scale of acceptable/ethical. 

Some monetize through advertising, as Unroll.me did prior to their acquisition. Some function as lead-generation tools. Some take your data and bundle it up into packages amenable to marketers (see: Gmail Sponsored Promotions). Some don't even sell your data, even though they're commonly cited as doing so. They buy it.

There are lots of ways to skin a cat. Unroll.me chose the unsophisticated and back-handed sale of email data without taking necessary safeguards we should expect from "freemium" products monetizing on our information (from HN):

I worked for a company that nearly acquired unroll.me. At the time, which was over three years ago, they had kept a copy of every single email of yours that you sent or received while a part of their service. Those emails were kept in a series of poorly secured S3 buckets. A large part of Slice buying unroll.me was for access to those email archives. Specifically, they wanted to look for keyword trends and for receipts from online purchases.

Lastly, incentives.

Facebook, Google, and Twitter have a lot riding on the fact that they can properly "anonymize" and protect their users' sensitive personal information. They have to keep users around, or they will die. 

Slice Intelligence, not so much.