It's also only available in the US, I believe.

In the case of Starbucks, they're taking advantage of an API within the Messages app, so as long as a third party implements something similar to what Starbucks is doing, I assume any other banking app could do the same, like Zelle could theoretically have their app allow you to just send cash via Messages if they implement the code needed for the Messages app. Now whether or not Apple would allow it is another story. I appreciate them gate keeping garbage from their app store, but they shouldnt just gate keep things they themselves do, its anti-competitive.