Comparisons between petrol (gas) and jet A1 need to be made with care - their properties are radically different. The stuff for spark ignition pistons engines is MUCH more volatile than Jet A1. During refuelling, petrol or Avgas will generate a significant area around the nozzle that is within the flammable range. For Jet A1 it will be much more limited. In addition, the ignition energy required for petrol/Avgas is much less than for Jet A1.
These are the main reasons why it is reasonable to refuel Jet A1 engines running, but not Avgas.