I think anecdote, personal experience, and most importantly, history, are valuable when the groups in question (law enforcement) are collecting the data in question. Would you believe a survey taken by Coca-cola about what soda is the tastiest? A lot of the initial reactions of law enforcement to incidents of police brutality start with denial, and they don't change their story until there is video evidence to contradict them. In so many incidents where there isn't publicly available evidence, they get to shape the narrative. No amount of data are meaningful if the source benefits from them supporting certain hypotheses.