Here is a passage from one of my favorite economics textbooks:

When physicians must be licensed and new drugs approved by the Food and Drug Administration (FDA) before they can be marketed, buyers are spared the cost of evaluating goods whose quality most of them would be unable to assess for themselves, except at prohibitive costs. By compelling sellers to obtain certification, government agencies can enable us all to make satisfactory exchanges at lower cost.

Find the unstated assumption and then evaluate this assumption.

If you know the name of the textbook and the authors, please don’t reveal it in the comments section. I will do so in an update.