What's happened to PETs?

Given that many candidate technical elements have been available for some time, it seems strange that Privacy Enhancing Technologies (PETs) have achieved neither widespread implementation in mainstream products, nor visible adoption by individual data subjects.In this paper I suggest some possible explanations, and set out some of the privacy-related problems which PETs could be aiming to address in today's online world.I then describe an application of “S-curve” and maturity models to the analysis of this problem, and conclude by using it to examine the success factors for adoption of innovative privacy-related technology.