Underlying causes include: in many US states, the District Attorney (chief prosecutor) is an elected position. In many US states, local judges are elected.<p>A major winning strategy of the last hundred years or so is the "law and order" platform, in which the politicians exploit racism, classism and even ageism to provoke fear of violent crime. The politician promises that they will increase arrest rates, win trials, and impose higher sentences in order to protect the [white, middle-class, elderly] citizens from the [black or hispanic, lower-class, teenaged] hoodlums.<p>And they win, and they put these policies into effect.<p>Do they work? Well, they work at getting the politicians re-elected, and that's the only real success criterion.<p>It turns out that if you ask Americans what to do about most issues, and you phrase the questions in non-aggressive ways, and you invoke empathy -- they mostly agree that treating people kindly is important. That innocence should be an absolute defense. That everyone should get necessary health care, and nobody should starve or be cripplingly poor. That people should work if they can, but not be abandoned if they can't.<p>But those positions are not very effective for the media and politicians, so they go with what works for their goals instead.