This same situation can occur with rigging grips,rigging gaffers as well as special effects co-coordinators. If an accident happens on set the dept. can or may be held responsible. If ,because of fatigue cased by hours of work, or short turn around,or simply being forced to cut corners by imposed time restraints, the accident is considered to be caused by negligence the party could face criminal charges.
But it is the producer's negligence, in his scheduling killer hours, that is to blame for most accidents on the set, and on the roads after wrap. All the producers understand is MONEY - the first time a producer is imprisoned or fined heavily ($MEGABUCKS$) for killing crew members with long hours, all of a sudden such long hours will no longer be necessary - hours will be reduced to human levels, shooting schedules will be extended, etc. Just like a bartender or party host is liable if a patron/guest drives away drunk, a producer should be liable if a crew members drives away exhausted. Sleep deprivation is just as dangerous as intoxication, once you get on the highway.