What I understood is that AWS is more than dogfooding. It is something Amazon first built for themselves, to give more independence to individual teams. And as they noticed it worked well, they realized that they could turn it into a product.

For what I understand as an outsider, Google is much more monolithic, having a platform where each team can do their things independently is not really their culture, so if they build one, it is only for their customers, because they don't work like this internally. Whereas for Amazon, an AWS customer is not that different from one of their own teams.