Workaround: install the Google Opinion Rewards app which is even available on iPhone. It will ask you survey questions about places you have recently visited. (Yes, it tracks you). Over the course of a year, you can earn $20 in "virtual" money which can then be used to purchase the 100GB/year plan.
You can (I do) earn that much without location sharing. But I've been doing it for a long time so I seem to get more surveys than I did at first. Looking at my history, I average just shy of 1.75/month.
