The loophole in the law is that the business can refuse cash if they have a device to accept pre-paid cards instead.
https://kdvr.com/news/local/do-denver-businesses-have-to-accept-cash/
I’m not advocating against cash per se, just on the side of the business who doesn’t want to accept cash as long as they are willing to forego the business.
“The loophole in the law is that the business can refuse cash if they have a device to accept pre-paid cards instead.”
You might want to take a class on reading comprehension ...
There are special pens that make a colored mark when drawn across bad bills.