If an artist can keep a secret apartment in plain sight, couldn't They do the same?

The Providence Journal is reporting that a group of artists assembled a rudimentary 750 square foot apartment in the parking garage of the Providence Mall, and lived there for up to three weeks at a time until mall security finally discovered them - four years after they started the project. Construction of the apartment involved smuggling cinder blocks, furniture, and a Playstation 2 into the garage; all told 2 tons of materials and furniture were involved. Now that they have been discovered they face some legal trouble, but that's not what caught my eye here. The real problem was that Providence Mall security somehow overlooked this apartment for four years. (By contrast, a burglar did find the apartment, and made off with the Playstation.)

Providence isn't a target in the way that New York and Washington, D.C. are, but think of the amount of weapons, explosives, and operatives you could hide in 750 square feet - that's bigger than my house. The garage is very close to I-95 (an exit ramp leads into it), and not very far from the Amtrak station.

I don't mean to be alarmist, but between Oklahoma City, the World Trade Center (twice), Madrid and many other incidents, can't we at least check out the darker, unused corners of our parking garages from time to time? Remember that the Oklahoma City and 1993 WTC incidents involved bombs placed in garages.

I mean, please.