Granny fuel
I've run into a few different definitions of "granny fuel" from pilots but a common one seems to be "fuel that is added to the tanks to account for fuel quantity gauge error, and is not shown on the weight and balance". Granny fuel essentially applies to fuel added to the tanks and not shown on the weight and balance, regardless of what the reason is.
This seems to be unsafe as well as illegal for a number of reasons. I've talked to pilots about this and it just seems that most refuse to acknowledge they're doing anything wrong. They come up with justifications for it such as asking if I would trust my life on the fuel gauge being accurate.
Are others encountering this in their airline operation? This is specifically regarding a large, twin-engine turboprop airplane that carries up to 19 people.