What is it about Melbourne that attracts these Sudanese?
The answer to that would be the Victorian premier:

His name is Daniel Andrews. He's pretty much an SJW masquerading as a politician. Loves migrants, loves diversity (read non-white), absolutes loves them/it. So much so when he gets the opportunity makes formal requests in writing to the federal government to allow "the Victorian people" to take any and all refugees that either try to arrive to our shores on rickety old boats or are currently sitting in offshore detention centres. As you can see from the ones he has taken, it's working out quite well.

Loves the teachings of Marx as well. He regularly appears on left wing programs trundling out Marxist propaganda and empty platitudes, in particular the "diversity is our strength" bit that commies like to come out with. Like most on the far left, he's subscribes to the following (not an exhaustive list):
-He's an apologist for Islam (he likes to call anyone speaking against it "racist", "bigot", etc, and promote the building of more mosques)
-Pro mass immigration
-Pro gay marriage (we currently don't have it legalised here)
-Pro abortion (ironic given that he describes himself as a "devout Catholic")
-Pro Black Lives Matter
-Pro transgender (he's actually implemented compulsory gender studies within the public school system in the state called the "Safe Schools Program", supposedly with the purpose of stopping bullying and "save lives", but the mastermind of the program has been caught on camera saying its' actual purpose is to put transgenderism in schools)
-Believes in the gender wage gap
When he's confronted with an opinion or a view in opposition to his own, he likes to assert intellectual superiority toward anyone with a differing opinion and routinely heckles them, which seems to be the go to strategy in the leftist playbook. He's capable of some Trudeau/Swedish politician level retardation if he's operating at peak levels.
Since he's been in power, it's no surprise the crime rate in the state has skyrocketed to the point it's become an election issue; there's an election due next year, I think. From what I understand, he's not polling too well, but also for a whole host of other reasons, primarily because he's turned Victoria into an even bigger nanny state than it was before. I don't live there, but I know people who do and am constantly hearing about the half baked shit they're subjected to on a daily basis, although I wouldn't say the rest of the country is free from this garbage either. We're not at Sweden levels yet, but we're certainly making a pants shitting run toward the finish line.