Objects can be destroyed if the damage points required are inflicted and it
has a down time. Perhaps the MA maps in question have them designed in
such a way to only have 'choke points' but the designer didn't want to hinder
GV flow entirely.
go try it for yer self in the MA it does not work you can't kill bridges of any sort
I once took a B29 with 40 500s to kill a railroad bridge it did not go down and I made sure I hit it I made several low passes lining up on the bridge and dropped all 40 on it at the same time from about 1500ft AGL
I even once tried to kill a supply convoy bridge with a KT I had all HE rounds and used everysingle one it did not go down
I suspect it is like the runway not being able to destroy even though it has a list as 108k of ords to kill it