Tyler Cowen does not expect the male birth control pill to be popular. Nor do I. He lists several possible reasons but misses what I think is the main one: incentive structures. As any woman can attest, it's all too easy to miss one or more of those pills. It's therefore very difficult to trust someone else to take them. It's especially hard if you are the one who will bear the heaviest price for a failure. As long as women have the stronger incentive to avoid pregnancy, it will be easier to trust them to keep taking their pills. Especially if you don't live together and thus can't watch him taking it at the same time every morning. The transactions costs on making a Coasean bargain are simply too high.