Context: I’m a middle class white dude.
If I pay cash, with a big bill, and the cashier or waiter holds it to the light to check for the security strip I don’t really think any thing of it.
That said, tonight at the grocery store a rather shabbily dressed black gentleman paid for a small amount of groceries with a fresh Benjamin. The cashier held it to the light, as is her job, and my gut reaction was “racist”. Which is just weird. Maybe I’ve just been hitting the old NPR too hard.