We have imagined "contextual advertising" as a simple system that sited advertisements based on the subject matter of what users are looking at. In fact, these systems make sophisticated use of whatever other data it can get about a user.

The conclusion I reach is that we should require systems not to be able to get any other data about individuals and not to require people to non nonfree software.

The Uber example is telling. Uber places ads based on where someone is traveling to. It can do that because it runs nonfree software (a cr&helip;app) in the customer's computer. It also uses whatever it knows about that particular customer (whom it has identified on each trip).

We should not allow companies to require (or pressure) customers to use systems that make them vulnerable to tracking. Privacy is a human right, and businesses are not entitled to human rights. So it is justified to regulate business practices simply to prevent businesses from deducing too much about humans.