I think it's the culture/genes they were brought/born into. Because it can be genetically made into your DNA or you might be raised in that certain household/culture that you're used to.
The way their tongue moves is indeed the simple explanation. For example, in France certain parts of their mouth sound certain letters differently than how it is pronounced in English. Being trained to speak one way, then having to do it the opposite way, is tough, to say the least!
The hazard prevention or control method that applies to such a situation is maintenance of the facility where the hazardous materials are kept and regular checking of the equipment's of fire control. This methodology can actually become the lifesaver for all the workers and employees in the workplace.
