I promise you it isn't about a big check from Google as much as it is about being able to control and manage the new platform to create new revenue streams via subscription. Soon, you will be forced to "rent" or subscribe to what are generally accepted luxury features in current vehicles. Since Apple controls CarPlay, GM wants an avenue to charge you big bucks for simple, desirable features. That's all. This will be more common as time goes by.
"Your air conditioner provides basic cooling down to 75 degrees. Should you want cooler air, simply subscribe to GM's 'ICE Package' and have the ability to turn the thermostat as low as you wish. Daily, monthly, and annual plans are available."