I think that would be for the "full Google experience" with Google-branded apps. If you choose to go plain Android with your own apps instead of the Google ones, you should be free.
Without license one also loses the name 'Android', the good deal on Google Ads and access to the store. All telecoms and big phone companies do pay the fee.
True. Android is Google's trademark, much like you can't fork Red Hat and call it Red Hat or have little red fedoras in its icons.