Considering that final reserve is typically only 30 mins, it doesn’t take very long to get down to these sort of numbers once things start going pear shaped.
The bean counters sitting in their offices with spread sheets aren’t dealing with an ever changing environment of weather, ATC, and operational factors. I’d love to have one of these guys in the flight deck when the weather is deteriorating and the expected approach time gets extended because of FOD on the runway.
Final reserve fuel needs to be 60mins minimum, if that adds a few pennies to the price of a ticket then so be it.