Bank robberies are one of many illegal activities that criminals may participate in. The take all depends on the amount of cops present at the scene. Basically: Higher Difficulty=Bigger Payout. However, I think it would be cool if you could put some more creativity in the planning and perhaps even complete a majority of the heist in a cop-free phase. Police chasing the crew after the scene is inevitable, but atleast there wouldn't be cops swarming when you crack the vault (with a lot of added effort of course to pull off). Perhaps even being able to tip off inside workers to arrange something that'll help the crew such as disarming the radio transceivers that detonate she packs in cash or looping camera feed.