Why might the management of an organisation not consider health and safety to be a priority?

This is an interesting question which goes instantly to the heart of a number of  important questions about the free will, society, and the nature of organisations.  In purely practical terms, it takes us straight to the difference between capitalism and anarchy. 

Any organisation should have the health and safety of its staff right at the bottom of its list of priorities.  The purpose of an organisation is to do whatever the organisation is for: in a company this is usually produce a return on the shareholders' investment.  The Health and Safety (HS) way of doing something is very rarely the cheapest, and therefore the Directors of the organisation are morally obliged to ignore HS.

This, of course, is bad for the staff and bad for society, which has to bear higher costs in the long run.  In other words, for the company to create wealth, HS must be a low priority: but for society to make wealth, HS must be a high priority.  (In a low HS environment skilled workers die, which is a waste of the investment in their training and experience.) 

Thus, a capitalist society makes HS a legal requirement.   This in turn provides a direct link between capitalism and democracy:  a democracy would also make HS a high priority, since it is ordinary people (i.e. the majority) who benefit most from HS legislation.

We see this in the real world: in general, the more democratic and capitalist a country's system of government is, the higher the standard of safety required.