Well it depends on which blockchain you might be referring to. Slapstick is a more controlled platform which allows us to stop the wild wild west from ever occuring in our blockchain. If miners do not abide by our basic rules they will be kicked off the blockchain. Miners can impose some of their own rules or own costs and are reponsible for the overall consensus of each block in the chain. If you are interested in becoming a miner email us at firstname.lastname@example.org.