Most business are terrified of a false positive so they over index and end up with an excess of false negatives.
They’re so scared to give something (for example, a refund) to a person who doesn’t deserve it that the end up not giving it to the majority of people who do.
This attitude permeates the corporate culture. (Btw culture doesn’t equal those “values” you put on the wall, which is actually poorly disguised marketing, it’s what your employees believe and how they behave. And they get that top down.)
There will always be assholes who’ll abuse your goodwill. Deal with those individually but don’t let your brand erode and your culture suffer because you wanna make fraud airtight.