The news report used emotive language to build empathy with the unarmed father, but the public wasn't interested. They obviously saw it as something unlikely to happen to them, or reflect on them.
Blue Lives Matter was one of the responses to Black Lives Matter - showing that a zealous section of the public identifies with the the police, rather than seeing them as a problem.
The Walmart shooting was going round Twitter & no one cared - possibly because gun control campaigners were being vocal.
Footage emerges after grand jury declines to indict police officer who shot John Crawford III, and differs from account of 911 call
www.theguardian.com
Things catch fire for a lot of different reasons, a lot to do with timing & personalities.