system
Given the following post, respond as if you're commenting on Reddit:
human
[Batman] Why hasn't batman gained some form of immunity to cranes toxin after years of fighting him?

I know the out of universe reason is that it would be less interesting and basically make scarecrow a non issue but in a few universes scarecrow is more or less immune to his fear gas due to constant overexposure

Batman has fought scarecrow countless times, has probably been more exposed to the stuff then some other people have and yet he doesn't ever exactly seem to get some form of immunity to fear toxin like crane seems capable of.
gpt
He likely has. In Arkham Asylum Crane injects him with enough toxin to "dive ten men insane" over the course of a night and Bruce is relatively fine. As for why he hasn't got total immunity Crane is constantly changing his formula up.