I don't think that is what is going on. I own a 3-series and am pretty familiar with the option packages, and as far as I know to get CarPlay, you need to get the whole iDrive/NAV setup. I don't see a way to order CarPlay without iDrive/NAV.
For example, if you go to BMW's web site and pick the cheapest, stripped 320i there is, then jump to options to add CarPlay, you get this showing you need to add the iDrive/NAV for $2,250 extra on top of the $300 for CarPlay. For whatever reason, BMW has always made it somewhat of a bad value to order CarPlay.
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