We are so amazing.
Note: dead bodies, unembalmed, are NOT TOXIC. They need to be handled with the same kind of precautions as live bodies. They do not contaminate soil or water. Trust soil.
Corpses are less scary than you think.
They are not only not necessary, but they are mispresented or misunderstood: Bacteria, not fungi do most of the decomposition. Further, we know from soil science that added microbes are nearly always quickly eaten by the local soil biota. Save your money and trust soil. Homage to the creators though for fostering further awareness of natural burial.