Why can't a decaf cafe misto be made?

Random question but three locations now have told me it isn't possible to make a decaf cafe misto but they can make me a decaf americano with milk... which like, is not the same thing?

I can order a decaf pike at all of these locations. I can order a regular cafe misto ... but they cannot make a decaf cafe misto... what am I missing? Is it not just coffee with steamed milk? I never want to argue with a barista so I have been getting the decaf americano but bleeghhh.

Thanks for entertaining my ignorance, I appreciate your insight.