Wow how many reverse geocode requests does a google API key make to get a bill into the thousands!?
Maybe a good iteration of this is use the .01 accuracy line work for the 99.9% of users but anything within 100m of a border could be sent to google API to get the edge cases. Probably would be in the free tier.
Yeah I wonder if maybe they weren’t caching the responses locally and repeatedly sending their requests to Google. I run a site which gets 1.5M unique visitors a month and we use Google geocoding api, and it comes out to $0/month, because our usage fits in their free tier.