and how do you propose that a female plant notices a male plant nearby?

I think that predisposition towards heraphroditic state is mainly genetically influenced. I only say this cause some strains almost never herm, C99 is known as a hermie resistant strain while others will throw out male pods like crazy. Thai's are notorious for going hermaphroditic.

Yes you can just trim off male flowers, but you'd need to pay constant attention, like several times a day, otherwise you could get one pod to open and then all your plants are pollinated. Not worth the risk IMO.