I'd add that if those Bradleys blowing up is just a single piece of information fragment, not the whole picture, the same should count towards artillery being there or not being there.
If the local commander knew a Ka-52 was going to have some target practice, the rational choice would be to allocate artillery to a different area, where it is more needed perhaps.
I do believe that due to the armada pulled into those areas and liberal use of Himars etc Russian arty is properly not working as effective as it would otherwise, its nowhere near non existant nor irrelevant. Plenty of dead to prove that point wrong.