Equal treatment under the law needn't be as you present it. If leave due to a child (eg, birth, adoption, death, illness) is necessary, it could be awarded on that basis of such a need.
Hey, me too! Usually.
Many rights typically associated with one gender can be worded such they'd apply more generally. This has advantages in handling unanticipated needs. (I recall a genetically male person becoming pregnant recently. We may expect more such novel events.) It also forces people to think outside the box. (Please excuse my use of that cliche.)
I get what you're saying but until men can truly bear children then I probably have the best example in this thread.
I WIN. HAHAHAHAH
I'm just kidding. =P