1. The cash doesn't have to be withdrawn all at once, it can happen over the course of months 2. The cash can come from earlier cash transactions, not withdrawal 3. Payment can be indirect: CEO donates to a non-profit that hires sheriffs family 4. Instead of kickback the CEO can repay the sheriff with another favor at future time

I hope we're not planning to outlaw cash and implement total invigilation of every transaction just to make corruption slightly more inconvenient.