Farmers know how hard it is to get rid of mites in a chicken coop.
Sometimes the only way is to burn it to the ground, and then treat the dirt where the coop stood. Treatment isn’t easy in a human home, either.

Mites rapidly evolve resistance to pesticides. In addition, mites can hide inside books, wood paneling, etc., during pest treatment.

Pest control professionals realize there is no test to prove that a building no longer has mites.
As a result, a pest control company typically will refuse to represent in writing that the mites in a treated building are gone.

The most accurate way to check the effectiveness of pest control efforts is to treat a home and then see if a susceptible person is still bitten.