Anyone can be taken unaware. It is impossible to be 100% paranoid all of the time. You have company over, there is a knock at the door and you don't think, but just answer, or perhaps family or friends forget to lock the security door.
For myself, if I come home and am greeted, I have a monitered alarm system. I have to punch in the code, but there is a "special" code which shuts down the alarm, but informs the security company that this system is being deactivated under threat...
Now, consider getting a gun and having a running gun battle with 5-6 armed indivuals.
Perhaps they are wearing vests, which mean that all of your shots will have to be "head" shots. This while engaging 5 armed men...are you sure your that "good".
What about family members, or neighbors who might become the innocent victims of gun play...Your best bet is to try and "play" along because your not really going to have a heck of a lot of choice. Once they have penetrated your "layers" of security, your pretty well defensless. I know, your still thinking that you can grab that AK sitting behind the couch and show them a thing or two, but again, your up against a group which has planned for your take down.
Now, you have to ask yourself, what is it about you, your house, your family, your job, which has brought you to this groups attention. Is there some kind of pattern there. The area you live, are you a bank president, do you carry, or have a job which involves lots of cash...what are they stealing, antiques, cash, guns, jewerly, if so how do they select their victims...
No, sooner or later, one of these guys will make a mistake. They will "brag" about their exploits, begin showing conspicous consumption, get drunk and beleive they are king of the hill.
In the mean time the police can only be reactive. I suppose they don't want to alarm the city can create mass panic.
I know of one case, where a silent alarm was triggered, the police put the buglars under surveillance, followed them, watched "who" they went to with their stolen loot, who they partied with, did an intelligent gathering mission...probably the same thing is going on here...sooner or later one of this group is going to screw up..then they will fall!