Unintentional consequences of the California three strikes law perhaps? Prosecutors unwilling to hand out mandatory 25 year sentences for petty theft?
Under Penal Code section 667(e), you can receive a life term if you are convicted of a serious or violent felony AND you have twice before been convicted of serious and violent felonies. See https://leginfo.legislature.ca.gov/faces/codes_displaySectio...
[1] https://www.nytimes.com/2015/02/27/us/california-convicts-ar...
[2] https://www.cbsnews.com/news/60-archives-steven-bell-the-bic...