Some of us have been saying that for years... care to speculate on why more options are available to women when both are equally responsible for conception?
Yes, 1 of the biggest problems has been that sperm is in constant production on an as and when basis. A woman's cycle is cyclical and can be manipulated.
Even the most recent advances in male contraception still requires a physical barrier to prevent sperm from being released ie a temporary vasectomy using an injectable substance that blocks the tubes.
I suppose the holy grail will be a pill that can block sperm production though the downside is that a reduction in testosterone leads usually to erectile dysfunction which kind of removes the need for a contraceptive