What are the most common reasons that people tend to run out of fuel/need the fuel rats help?
Sometimes people run with half empty (or lower) tanks trying to push a bit further into those sparser regions where the stars are a bit further apart than you can jump with a full tank.
Sometimes people are jumping along, topping off as they go round stars, only losing a few percent of a tank in aggregate for most jumps and stopping for a complete refill only when they need to.
There is a layer of mostly brown dwarf stars across most of the galaxy around 60ly below the zero plane. If you are close to it the route planner will sometimes drop into it for an extended period and sometimes it's a good way to get across an other wise spare area.
Sometimes people are just jumping around in the Neutron Fields scanning those high value but unscoopable stars.
In all of those cases a momentary lapse in concentration can leave you sitting in an unscoopable system without enough fuel to jump out. (I got bitten by the second one, as I burnt off fuel I got one more jump than I'd been expecting but I didn't check the star and *boom* sitting by an L class star without the fuel to escape, 55kly from Sol).
There's no secret mechanic that'll steal your fuel, it's carelessness - however momentary it may be this is not a gentle game that holds your hand and comforts you.
