Could you elaborate your question, maybe it's just me in this case, but I don't understand what is your point. If really someone asks you USD 100 promising to send you USD 1000, do you really think it's not just a scam for example from Nigeria ?
I have seen many use the carding tricks. But I do not know about the wire transfers Western Union. It seems they steal it from big banks (who cares about them) and wire it thru western union. In some countries, this is very good if legit source.
They don’t rob banks they have spyware installed on thousands of pcs called botnets and prey on someone who’s already got wu account for example and do a MITM attack.