While Android has supported disk encryption for a while now, Android 5.0 is the only version that implements it by default rather than having it be opt-in. However, many recent smartphones running Android 5.0 have shipped without default encryption which means that Google has, at some point, decided to relax that requirement for reasons unknown. This may be due to the decreased performance in many devices because of encryption.  

Last year, Google made headlines when it revealed that its next version of Android would require full-disk encryption on all new phones. Older versions of Android had supported optional disk encryption, but Android 5.0 Lollipop would make it a standard feature. But we’re starting to see new Lollipop phones from Google’s partners, and they aren’t encrypted by default, contradicting Google’s previous statements. At some point between the original announcement in September of 2014 and the publication of the Android 5.0 hardware requirements in January of 2015, Google apparently decided to relax the requirement, pushing it off to some future version of Android. Here’s the timeline of events. Google’s decision to encrypt new Lollipop devices by default was reported widely, in both tech-focused and mainstream publications.