Oddly enough the way you find it out is to read the police reports. They do keep track of it. Because no one cares. Of course the amount they report might not be the amount they took. You can see the Afroman videos to see how that works.
They are now training "cash dogs" that will alert on people carrying cash. Not drug money or anything like that. Just cash.
“They are now training “cash dogs” that will alert on people carrying cash.”
Hmmm... that’ll come in real handy when CBDC goes into law, and cash becomes illegal.