Dennis Dale points out in The American Conservative:

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!

By the way, by relying on Google Maps crowdsourcing, I got the precise location of bin Laden's compound wrong in the busy hours following bin Laden's execution. Google Maps put a pin on a similar sized compound a little farther out of town than the actual one, which lies between the center of Abbottabad and the Pakistan Military Academy.

Bin Laden's place was more conveniently located to the venerable Abbottabad Golf Club than I had originally thought. I apologize to whomever lives in that big compound I pointed to. On the other hand, I wouldn't be terribly surprised if that guy got to own that big estate by, oh, I dunno, accepting bags of cash from the CIA to look for bin Laden ...

Bin Laden's three story building was built in what was then an open field no more than a mile from t he front gate of Pakistan's West Point, which has 4,400 cadets and about 600 officer / instructors. There are also operational units of the Pakistan Army based in Abbottabad. The average person in Pakistan doesn't ask a lot of questions about what the Army is up to, with ample justification. On the other hand, Pakistan's military-intelligence complex asks lots of questions about lots of things, especially who is building a fortified compound right in the intellectual heart of their power. The only way they couldn't have not found out that bin Laden had decided to infiltrate their front yard was if they had done the deciding for him.