Companies are quietly using your personal data — even your facial expressions — to decide how much to charge you, and it is bad news for anyone who shops or rides with a phone in hand.

• Apps have been caught selling location data, and driving data has been passed to insurers, pushing people's rates up.
• Some drugstore chains have put facial recognition in cooler doors to read shoppers' moods and steer them toward pricier items.
• Ride apps are suspected of charging more when your phone battery is low, because a dying phone means you cannot shop around.
• The common thread is simple: the more a company knows about your situation, the more it can charge you for the same thing.

Outlook: Expect this kind of personalized pricing to spread as data collection gets cheaper, unless regulators step in.