If you as the question as "Hey Siri: how many days until the end of the year?", you get a valid response. I intuitively guessed that the word "until" was a trigger that would make Siri understand what I meant.

In other words - it's not that Siri isn't _capable_ of doing things like ordering medication, but that the syntax for doing so is still obscure and specific enough that most people aren't using it for purposes like that.

I've set up a number of shortcuts that I regularly use. For instance: "Tell my wife I made it" will send her a text message letting her know that I've arrived wherever I was going. "Tell _them_ I made it" will send the same message to my wife, daughter, and mom.

Until the NLP algorithms get better at inferring intent, a combination of user training and custom shortcuts will be needed to do things like this.