Who would you ask to watch your laptop for a moment?
All things being equal, we pick the person most like us (looks, acts, speaks, thinks like us).
When we think someone is one of us we're more wiling to trust them (and they're more willing to trust us). If we feel someone is one of us, we're willing to put them before ourselves. This is a prosocial behaviour.
To know if someone is one of us we look for signals. That includes how they look, act, dress, and speak. The more signals we recognise, the more we categorise them as one of us.
If too few people are willing to help a group struck by tragedy, it's not a media problem (the media reports on what people care about), it's a kinship recognition problem. We're not willing to sacrifice precious resources for people we don't consider in our group.
The only solution is to find the shared symbols (which act as signals) which would help embrace the other group as kin and enable prosocial behaviours.
More practically, if you want different groups to help one another, you have to show why they're similar – not why they're different. You have to find the shared symbols (objects, ideas, beliefs, actions etc…) which unite them.