That's not what he's describing. In this case there actually is no cash or traditional ATM involved on-site. It's connected to the dispensary POS, not a physical ATM. (They often have a regular ATM like you describe also, though.)

So you do an ATM transaction, but the money goes to the dispensary somehow. I do not know how it works on the back end, but I've used it as a customer. It's lovely and can even be done over your phone.