Caring is overrated. Unless one does something about what they care for, it's not just useless but also harmful (e.g. stressful to the person caring with no effect towards solving the problem).
If somebody doesn't want to care about something the "reason" they give is likely not important, at the end of the day it's an emotional decision. If you want to make people care about something, I recommend offering them a situation where they can sleep better at night when they care.
"The statistics of large-scale killing don't convey emotion"
https://www.npr.org/sections/health-shots/2018/11/09/6661503...
Single incidents sparking outrage are a force in society that we are not going to get rid of any time soon. The last thing we need is people outraged over an incident of slavery to be told to be apathetic, as the people who help promote it, which now apparently includes facebook, aren't going to suddenly be all reasonable if everyone shouts less about single incidents. While the solutions that are required may be structural, everything ever complained about is an incident.
Nail the fuckers somehow. That is not OK.