Dashcam evidence is useful on some occasions to prove that the driver of the camera-equipped vehicle was not at fault.
However, sometimes such a recording might be prejudicial to the interest of the driver. Although there may be no actual legal liability, the exclamation of "YES ! RESULT !" on the soundtrack as another suicyclist is efficiently yet messily despatched to the hereafter can make a poor impression at the coroner's inquest.
So, for those moments when the lack of an evidential digital recording might be beneficial, the latest dashcam from BorgCo incorporates an "Irretrievable Bulk Erase" button that, when pressed, drives a very sharp hardened metal spike through the exact position of the chip in the memory card, destroying it beyond recovery.-- 8th of 7, Jan 25 2020random, halfbakery