Osama bin Laden’s fortress was heavily constructed–drone-proofed, it seems, when built in 2005. He avoided land-lines and stayed indoors. This is consistent with the need to evade the US and its technology. In contrast, his compound was very lightly guarded. This is consistent with a high degree of comfort–concerning the possibility of a ground raid.
Of course bin Laden discounted the chance of a US commando raid–anyone would have (in fact, that loud racket you hear is the sound of the president’s giant brass b**ls clanging together as he does his victory lap). There was no need to post a useless armed contingent whose presence could only draw suspicion. If and when we came it would be via airborne munitions.
What is striking is how completely bin Laden appears to have discounted the possibility of being raided by Pakistani forces. What confidence he had in the fidelity, authority and discretion of his benefactors, whoever they are!