Final answer:
Staff training is the option that cannot be considered a capital expense since it is an operating expense focused on enhancing the productivity of current staff rather than creating new assets.
Step-by-step explanation:
When we consider capital expenses, we are referring to expenditures that create future benefits by acquiring or upgrading physical assets or intellectual property. Therefore, software licensing and hardware purchases both are considered capital expenses given that they are used long-term to produce goods or offer services, and contribute to a company's capital base.
On the other hand, staff training is generally treated as an operating expense because it is more about maintaining the effective use of current assets rather than creating new ones. Hence, staff training cannot be considered a capital expense since it is not creating a new asset but rather enhancing the productivity of an existing one. The development of training materials may have elements of a capital expense if it results in a proprietary asset that the company can use over multiple training sessions or has a utility in future operations.