I generally don't believe in accidents. I believe situations like this are caused by folks not paying attn., ignorance, or deliberate violation of safe practice/procedures. The probability that a fire would occur during the loading of A, or A1 jet fuel into a tanker in such an engineered environment is essentially zero. The fact that it occurred at all means that someone did something to change the conditions of the situation to cause the probability of fire occurring to be likely.
Not paying attention, ignorance, deliberate safety violations, all accidents waiting to happen.