There’s a theory that mainstream media outlets deliberately (or algorithmically) select and highlight news stories that are maximally divisive. The Eric Garner story got much less press than the Michael Brown case did, because the Garner one was quite clearly a case of police abuse. Only the most fringe elements would claim the police acted fairly in that situation. Meanwhile, Michael Brown’s death was (at least at first) in a much more fuzzy area. So, more controversy, more clicks and comments.