The best answer here is the last one: Public and government acceptance. That is how paper money is "backed" in the USA. I hope this can help you a lot.
I believe the answer is: <span> hygiene factors
According to herzberg, people see </span><span> hygiene factors in their working environment to have a strong relation with their physical wellness in general.
They would most perceive unhygienic working environment as a direct attack to both their physical and mental condition.</span>