Parking in a crowded garage is basically the bane of every driver's existence. You have to drive slowly, a turn taken too narrowly can rip off a side of the car, and once you park you're always at risk for door dings. Like in bumper-to-bumper traffic, parking in a garage is a natural place for a car to go autonomous.
Instead of using a bunch of expensive sensors that would make a Honda Fit the price of a beak nosed Acura, Honda wants to use the backup cameras as well as the security cameras at the shopping center in order to help the car park itself. They think that using the already integrated security infrastructure will make it cheaper to integrate in more cars.
The issue is that the tech would work only for Hondas, so if Toyota implemented a similar system, a Honda lot wouldn't park a Toyota, and a Toyota lot wouldn't park a Honda. Though I think it's in their best interests to make the system universal to everyone can take advantage.