It makes particular sense for vertically integrated conglomerates like Amazon-Whole Foods which owns Zoox.

I buy Whole Foods French fries shipped to the store via Amazon logistics and purchase those at Amazon owned Whole Foods, at a discount via my Prime membership on my Amazon credit card which is processed on AWS infrastructure and I ride home on an Amazon owned Zoox that also runs on AWS infrastructure.

Amazon owns so much of the profit margin across that stack that they can afford to give rides away for example.