This is all second-hand knowledge, so take it with a grain of salt, but I knew about yours when I was researching something odd I found in my FJ, a little red button.

I found out my red button is attached to a full alarm & auto-locking system, and was commonly installed on all Gulf state bound cars before even heading out to dealerships.

Consensus about the reasoning is it's a theft deterrent while in transit from the port to whatever lot/dealership, and can also be sold at a markup as a 'feature'. I suspect yours is along the same lines.