I care because I'd want someone to care about me too. Of course if I see something on the news I'm going to get emotionally hung up or cry about it, but sometimes it can touch a nerve. The immigration? Here in Australia we have a lot of that happening, immigration and refugees on illegal boats, because Australia is so remote they think they can get in. It affects me because I find that the topic is a real segway for racism and that just makes my blood boil. A lot of my relatives are a little bit racist, they have very black and white views that I sure as hell don't agree with. And I've heard the N word come out of my grandfathers mouth, and g**ks and bl**ky. It's a disgusting attitude. There is an Asian restaurant near my house and their sign is always getting smashed, the other store signs don't have a scratch on them, only the Asian restaurant. It affects me because this is where I live, and it's an embarrassment. Then I see more of it on TV and it's even more shameful.
As for the death of people, well sometimes death has the biggest voice, it takes a death for people to notice, it takes someone to commit suicide before people start to really care about mental health, it takes an overdose for people to really start to care about addiction, it takes the death of a police officer for people to really see the disrespect of people out there that we have to live with.
Not everything is going to affect everyone equally, but some people are more sensitive to things or passionate about things than others.