Final answer:
The assertion that the true cost of a meeting includes the lost productivity is true. Opportunity cost represents the value of the work not being done while attendees are engaged elsewhere, like during a company retreat.
Step-by-step explanation:
The statement that the real expense of a meeting is the lost productivity of all the people attending can be considered true from the perspective of opportunity cost in business and economics. If we take the example of a boss organizing a two-day retreat for employees to build team spirit, we must consider not only the out-of-pocket expenses such as the fees for the consulting firm and room and board for participants but also the loss in productivity.
During the event, employees will not be engaged in their usual work tasks, leading to an opportunity cost which represents the value of work not done during this period. This is often a hidden cost and not immediately visible, but it is very real and could potentially be significant, depending on the number and skill level of employees involved.