Working At High Altitutdes is Differ From Different Region .Why?

For more than 2 metres, it is commonly defined as high level fall in which most injuries are resulted from. However, there is an increasing trend that there has been similar number of injuries from low level falls (i.e. less than 2 metres) and from high level falls. As such, some countries have deleted the “2 metre rule” as the definition of falling at height. Instead, it is newly defined as working at a place from which a person could be injured by falling from it, regardless of whether it is above, at or below ground level without stating the level of fall.

This question is taken from book named – A Self Learning Manual – Mastering Different Fields of Civil Engineering Works (VC-Q-A-Method) by Vincent T. H. CHU.