You have a person to reach out to if things go pear shaped, and N(weeks|months) to sort out payments issues instead of having everything get suspended by robots.
1. Because they'd probably have to hire several hundred humans and give them benefits. It's much cheaper just to trust the robots.
2. Unlike a small hosting company, Google is so big it will suffer essentially no financial consequences if their robots make a wrong decision for credit card customers a few times per month.
So there is no cost to Google for leaving the system as is, and a high cost for your solution. The decision is a no-brainer from their point of view.
