two reasons IME. one is that it's easy to adopt a just world hypothesis and our biases as humans play it up. imagine doing this on the reg:
- detain someone for something e.g. traffic stop for speeding
- find probable cause e.g. alcohol on breath
- find other bad stuff e.g. a gun or meth
- arrest and mutter under breath "got the bad guy, he deserved it, saved innocent lives" or w/e else
- go back to first step with an additional data point that speeders may also handle drugs and be driving drunk
two, incentives are what they are. police generally aren't rewarded for doing high quality year long investigations that uncover every particular fact in a meticulous and honorable way - there isn't $$ or staff. incentives suggest that closing them gets you farther than "doing a good job, for certain values of good widely held by the public". for the district attorney, they largely have the same incentives (throughput) and so prefer open and shut type setups or plea deals so as to get things moving quickly. so they aren't helping the situation either.
- detain someone for something e.g. traffic stop for speeding
- find probable cause e.g. alcohol on breath
- find other bad stuff e.g. a gun or meth
- arrest and mutter under breath "got the bad guy, he deserved it, saved innocent lives" or w/e else
- go back to first step with an additional data point that speeders may also handle drugs and be driving drunk
two, incentives are what they are. police generally aren't rewarded for doing high quality year long investigations that uncover every particular fact in a meticulous and honorable way - there isn't $$ or staff. incentives suggest that closing them gets you farther than "doing a good job, for certain values of good widely held by the public". for the district attorney, they largely have the same incentives (throughput) and so prefer open and shut type setups or plea deals so as to get things moving quickly. so they aren't helping the situation either.