It's cheap for weed, but expensive for a relatively high-volume part of a relatively easy-to-grow plant. Imagine seeing an $800/pound price tag in the produce section of your grocery store.
I believe the acceptable mold level in Michigan is 10x that of Ohio. Price is only one component, many people like a tightly regulated medical market to ensure safety.
If it were at a sufficient level for people to start getting sick you'd expect to see an increase in people with related issues, but you don't when you seek out news on this factoid, just a statement on the level being higher than in another place. Most products you consume will have at least some mold on them.
Or the tight regulation produces higher prices without any particular improvement to the product (e.g. taxi medallions). “tightly regulated” != “better”