My thinking is that machine gun nests are cheaper and easier to maintain. :-)
True, but mobility allows the use of fewer troops overall (my 2 cents) to cover the same ground. Add an intrusion detection system using cameras, sound or the like and the quick reaction force drops in to bag the bad guys. I’ll leave it to the pros to pick the best option - what they really need are mission orders to do the job. That comes from on top. Unfortunately.