I wouldn't carry $16,000 either but I have bought and sold motorcycles before with cash, maybe $4-6,000, and I certainly wouldn't want that taken from me by some shake-down artist posing as a cop.
I own a company that does, among other things, roofing work in an area often hit by hurricanes. Now when a hurricane comes through its quite literally "go time" for us and I am forced to withdraw tens of thousands of dollars. Why, because my guys still need to be paid (then more than ever) and it can take weeks for power to be restored. Debit cards don't work when there is no juice so I have to pay upwards of 150 men and women in cash. I even have a special safe installed just for that purpose but because of how absurdly busy we are at the time I pay them on the jobsite.
My only point is that there are legitimate reasons to carry that much cash even though I don't believe I should need such a reason to do something that is perfectly legal with my own, or my businesses, property. I should not be at risk of being robbed at gunpoint by the very government organizations that are supposed to protect me from being robbed.
Some departments even use extortion to get you to sign over your money with threats such as if you don't sign this waiver we will arrest you for "insert absurdly trumped up charges". This tactic is especially popular to use against minorities and travelers from out of town. Do I really want to go in front of some podunk jury in some podunk town in Texas over $5,000 or is it easier just to sign it over? Keep in mind that decision must be made on the side of the road without access to counsel.
To blame people who got robbed by the government for carrying too much cash is absurd and as another story illustrated you don't even have to carry it, they'll take it right out of your damn bank account. Not to mention that while they prefer cash that is not the only assets they can and do steal from you. Some departments really like fancy cars or even houses, often targeting people for criminal investigation based off of how much stuff they have to steal.
