As opposed to…what? Imaginary?

If you mean “how do they know it’s not counterfeit?”, the answer is “almost no money is counterfeit” so they just take the money they’re given. Estimates are that there’s only about 1 counterfeit bill for every 10,000 real bills.

Like everybody else dealing with large amount of cash. There are quick ways to check by eye and touch [https://www.wikihow.com/Detect-Counterfeit-US-Money](https://www.wikihow.com/Detect-Counterfeit-US-Money)

or special “pen markers” and lamps/machines to check the ink and paper is correct.

Edit: right now manufacturing modern US dollars it’s an extremely difficult technology to pull off. The source materials and the process it’s of course extremely tight.

Probably out of reach for criminal cartels, but not impossible to attempt for an “adversary nation” to destabilize the economy.

There is a historic precedent in ww2 Germany tried (unsuccessful) to flood Britain with fake Pounds notes

You don’t need the money to be real as long as who you give it to is even worse at spotting fake money.

The same as every other shop in the world. Counterfeit money is extremely rare (Well, except the old £1 coin, but that’s been replaced) and usually easy to detect. If they CAN’T detect it, chances are neither will whoever they then spend it with.

The same way everyone else does? It’s pretty difficult to make counterfeit bills and they don’t hold up to even casual scrutiny in most cases. You would know if the materials, textures, designs were off. And why would your average John want particularly to try and scam their dealer or prostitute? Sounds like asking for an ass-whooping to me!

People who work with cash often can spot a fake a mile away, down to the touch. The feel of be the bill(s) in my hands is the first tell tale than the visual inspection.

You literally just need to scratch a fingernail on the ink. A *real* bill will have gritty ink, a fake one won’t

Well a lot of drug dealers and prostitutes are using Cashapp now for payment. So they can be paid digitally without any physical bills. But how to know cash is real or not depends how new it is. One if it’s movie money it’s covered in stuff saying it’s movie money and the portraits are messed up and the bills are larger.

If it’s counterfeit and it’s supposed to be a newer 20$ or 50$ you can look at the gold 20 or 50 in the corner and turn the bill while in light. Real money the gold number shines and changes color a bit, fake ones don’t, they’re just flat ink with no reflection. And if you get a stack of counterfeit bills you don’t have to go through maybe six bills before the serial numbers start repeating.

The new 100$ bills are covered in too many deterrents to be faked. And if it’s one of the newer bills where jackson or franklin aren’t in a frame, you can rub their shoulder and find bumps there that give a tactile protection as well. One and five dollar bills aren’t worth counterfeiting.

In addition to the points here, there is also a threat of extreme violence if people try to rip you off.

The same way you know that money you get is real. You look at it and take the rest on trust.

With criminals there is the added issue that if they realize they got counterfeit money and suspect you gave it to them on purpose they will not involve cops or lawyers to seek redress but go through more direct and informal routes.

Even if no violence is committed word gets around.

For people who frequently deal with large amounts of cash, it turns out that you can get those counterfeit money detectors from amazon and similar, so there is always the possibility use that if you think it is a huge problem.