Arbitration is not public - so we would never know. That is not unique to Google either, it's just how it works.

My guess would be it happens far more often that you might realize, given Google's scale and breadth of services offered (paid and unpaid).

People have disputes all the time with big companies, and arbitration is how they are normally resolved. Arbitration is designed to 1) usually minimize the public risk to the company in the event of a loss, and 2) make the proceedings far more affordable for all parties involved.

Arbitration carries all the same weight and enforcement of a real lawsuit, but takes less time and is less costly.