I'm not 100% sure I understand why miner would prefer BU pools as opposed to other pools. Is it because the miners receive 100% of the mining fees? (as opposed

I'm not 100% sure I understand why miner would prefer BU pools as opposed to other pools. Is it because the miners receive 100% of the mining fees? (as opposed to having to pay admin fee to the pool manager) BU's income is the fee payed by successful customers. That means that there should be an equilibrium point between "miners for hire" (that try and target specific transactions) and regular miners.