It’s my understanding that most businesses that don’t accept cash don’t refuse it because they are afraid of counterfeit bills... it’s because the employees can just pocket the bills.
The local ball park in our town is that way. No cash, only charge or debit cards. Or else electronic payments.
That’s probably true.
I always pocketed the extra cash when the customer didn’t want their change, but I never stole from the business. I usually made an extra $5 over the course of my shift from change being left on the counter.