[jka]

There's no reason why free (as in either libre or beer) software has to incur privacy or subversive-practice costs -- see Linux or PostgreSQL, for example.

The issue is that the ad network economy, as currently structured, allows inflicting these costs against consumers -- who couldn't possibly keep track of them all even when technologically well-educated because there are so many apps, SDKs, advertisers and publishers -- while incentivizing application authors to take part with the assumption that they are safe in the crowd.

Rather than pay $5 for an app and hope that it won't misbehave now and/or in future, it generally seems preferable to use a competing free and open source application backed by a community that can inspect and modify it to add features and fix any discovered problems. When such software doesn't exist, it can be developed given enough demand and interest.