There aren't really any licensing fees for Android Auto. Apple charged a few dozen dollars for the right to produce a car with the integration, rather than a license as such. There's integration costs and hardware, so it's not free, but generally it's cheaper than the alternative.
Android automotive, the system GM is discussing here, is more expensive in every way than Android Auto. The reason they're switching is that Android Auto/carplay don't give GM enough additional monetization options for customers.
