aren’t there basic halachic rulings already in place that say when a couple can ask for a divorce or not?
Correct.
So shouldn’t a prenup only cover those?
It should. But the RCA/BDA prenup does not do that. The legal provisions written and signed in the RCA/BDA prenup allow the spouse to invoke the $150.00 daily penalty payments immediately upon demand, by simply walking out of the marriage for any reason or no reason at all.