Well if he wants 50/50, he's going to have to start buying son clothes...along with paying for HALF of school fees and school supplies and school lunches and school activities and extra-curricular activities and so on and so forth. Not too mention that his electric and water and garbage will increase, along with fuel costs and food. And he's going to split any time off necessary if son is ill or has doctor appointments. And he's going to have to provide time and transportation to be involved with son during his "parenting time".
A parent who REALLY cares about their child, is NOT going to care that it will cost them more.