Reasonably practicable means doing everything reasonably possible to keep people safe. Controls must give the highest level of protection and be the most effective and reliable, be available in the workplace and be suitable for the workplace and workers. Cost is relevant only after the risk and the options are identified and assessed, and there is a clear presumption in favour of safety over cost: choosing a cheaper option that protects less because it is cheaper is unlikely to be reasonably practicable. Resourcing pressure does not remove the duty. Other legal frameworks and standards that bear on managing the risk may need to be met at the same time as WHS laws.
The graph holds this control, the 0 it maps to, and the evidence behind each claim, over MCP and REST.