The problem with prison reform is politicans are incredibly afraid of being seen as "soft on crime". Paradoxically, this is especially true for democrats, because republicans are assumed to be tough on crime by default. Opposing prison reform is an easy way to seem tough on crime because convicts don't vote and most people aren't familiar with the prison system. Policing is more controversial, because a lot of people have had negative personal experiences with the police, and many are suspicious of government or authoritarianism.