Why doesn't streaming via Airplay to Airport Express work like on Apple TV with multiple devices?

I just got an Airport Express so I could stream audio downstairs in our kitchen, I also have an Apple TV 3rd generation. If I am streaming something to the Apple TV from my iPad and then my friend starts streaming to the TV from his iPhone, the Apple TV releases the iPad and starts streaming from the other device. Seems smart and exactly how I assumed the Airport Express would work.

But no. If I have one device upstairs streaming to the Airport Express and then start another device downstairs, I get an error message on that device saying "Airplay speaker not available. The speaker "Airport Express" is currently being used by someone else." Which means I have to go find the other device, stop it, and then start streaming from the one I want. Seems counter intuitive, or there should at least be an option when you get that error message to stop the currently streaming device.

Is there some other way to make the Airport Express release the currently streaming device? Will password protecting the Airplay on the Airport Express make it function like the Apple TV?