I think NEC is written vague enough on this that many AHJ's tend to default to worst case situations and it ends up being a classified area.
There are many cleaners/solvents/etc. used in these places that likely are more of consistent potential hazard than any motor fuel being used is and I think that somewhat a factor even though NEC doesn't really clearly state this. The fuel system of the vehicle IMO isn't much of a hazard except for when there is an operation that involves opening or draining the fuel system, or maybe an occasional failure of said system that is leaking fuel comes along.
These guys often use grinders, welders, torches or have other situations where "sparking" may end up in the classified area and there is rarely any problem with those things igniting the classified area. I can still understand wanting seals in raceways leaving those areas just in case though.