Additional context: there have been major airliner crashes resulting in hundreds of deaths as a result of planes put in holding patterns by ATC that ran out of fuel while waiting to land https://en.wikipedia.org/wiki/Avianca_Flight_052

The fact that airplanes that are low on fuel have absolute emergency priority has occasionally resulted in, uh, incidents: https://www.youtube.com/watch?v=D3RUWvRRGLQ