Unfortunately, it is probably also true that most non-financial managers do not know very much about it.
This is a pity because it affects so many business decisions.
For example, the fixed costs of running a cruise ship do not vary (or realistically only vary slightly) according to the number of passengers is the reason that large last-minute price reductions are often available. (Think of that when you book your holiday.)
A basic understanding of the principles of costing is important in business management.