now there's an idea... scaled difficulty and reward.
Think about it in real life... you mug someone in a backstreet, your chances of getting a lot of cash is minimal, and the risk of being caught is also minimal- slum towns have high crime rates, so people won't have large amounts on them. (downtown decatur)
But if you go uptown, and steal from larger houses, and richer people, the crime rate will be lower, and security far tighter. If you're good enough, you'll steal larger amounts, but the risk is greater. (midlan/rural)
This would also get the larger districts used more, and get more activity- at the moment, the only reason anyone uses midlan is a) to buy guns/houses or b) to rarely hide (kinda useless, since anyone capable of killing you can travel there, so wasted cash).
This would get those higher districts used. But there's no reason you can't have new higher level crimes available in higher districts too