Photoshop must have also a listener for 'Open from Cameraraw'
If you meant Photoshop "should have" such an event (instead of it "must have" one) then you may want to post a Feature Request.
As far as I can tell both Photoshop DOM and AM code feature some inconvenient "absences" …
Photoshop [ should / must ] have also a listener for 'Open from Cameraraw'
But it’s not Photoshop’s ACR that hands over the data but Bridge’s and the file has no path or fullname yet.
And as far as I can tell Adobe makes no claim that every Photoshop operation/feature is Scriptable/has am AM counterpart – which can certainly lead to an unsatisfactory Scripting experience, so I think you should post a Feature Request.