Because Audi views themselves as a performance brand over a luxury brand. They're also hungrier and thus more responsive to consumer demand.

BMW allows carplay with a monthly subscription to the rest of their services, largely because they believe that as long as you're getting the full benefit of a connected car, you'll be attached to the value - strategically, it makes no sense for them to give it away from free.

The other thing? These companies are starting to change their mind as consumers demand it as a feature.

I always knew there were good reasons I prefer Audi.

Although to be honest, if not for the unconscionable amount of money they (or Navteq, I guess) asks for map updates, I'd be even happier just using the built-in navigation all the time.