You may have a better understanding on this than I do as it's been awhile since I researched it. With apple much of the location info is actually kept on the device where it can actually make use of it locally rather than sent up to a cloud dossier on you. Google works very differently.

Opt in is a little disingenuous in both cases. If you choose not to opt in you basically have an expensive brick. The challenge really in both cases is that you have no idea what is actually being done with your data as the privacy policies of both companies are weak.

Primary point being is that if you look at the business models of these companies one is dependent on data collection and ads while the other device sales. Based on that I can infer what may be done with my data.