Spice and herb prices vary substantially based on the ability to grow them in large quantities, the difficulty of harvesting them, preserving and transporting them. Not surprisingly, expensive spices can also get diluted or "cut" with other substances. Based on the weight value of some spices, "cutting" may approach the value of cutting illicit drugs.
There is a great discussion of what is used to cut spices at Food 52 - https://food52.com/blog/15514-why-some-spices-are-so-expensive-why-you-should-spend-the-money#comments and at the LA Times on why spice prices vary greatly depending on where they are sold, such as the traditional way through grocery stores chains versus newer channels - http://www.latimes.com/food/dailydish/la-dd-calcook-shopping-dried-herbs-spices-20140304-story.html.
Many spices found in the spice aisle of the grocery store are not exactly fast moving consumer goods if compared to Pepsi or Coca-Cola products. However, there are tremendous differences even within the spice category. Considering those differences and the pressure on margins of the grocery stores and distributors contribute to the pricing chaos You can find a very detailed discussion about margins for Whole Foods Market suppliers right here - https://edsoehnel.com/whole-foods-market-markupmargin-numbers/
“Normalizing” the price of spices by charging the same price regardless of the spice would counteract the pricing chaos. It would make spice buying much easier and overcome at least one of the many consumer anxieties in the spice aisle.