Passport expediting is indeed a legitimate service. I do not understand how they can get in when a regular citizen cannot, but they do it. I used Zierer Visa Service (www.zvs.com) to get a new passport for my wife last summer.
They were great.

I have also used them for many years for visas to China. Actually, they have my passport right now for a new China visa.

I highly recommend Zierer's services.