I have absolutely no idea why they're trying this $600 stunt. Anyone that's trying to hide income doesn't just deposit and withdraw it in a bank account, they're usually using cash or one of the dozens, if not hundreds, of ways to launder money.
This $600 thing just seems like a way to go after the law abiding citizen and keep them in fear of their own government.
It's definitely against the 4th amendment and I'm hoping that the Supreme Court strikes it down.