Company A buys software from company B to carry on its business. Company B does not become liable for the acts of Company A.
A9 and A2Z are providing software and/or services to Amazon.com which Amazon.com uses in its retail business. This is completely different from A9 and A2Z engaging in that business. They do not buy, sell, distribute, or ship the products Amazon.com does.
So long as Amazon.com maintains arms-length dealings with A9 and A2Z (which is trivially easy for any company with semi-competent legal counsel to accomplish), the ownership of A9 and A2Z is irrelevant to Amazon.com's dealings with California.
Not really, no. As far as I can tell, they all provide products or services in some for to end users outside Amazon.com's retail business.
Not that it matters. The principles are well-enshrined in the common law system, codified and uncodified. You may think it's ridiculous, but the courts take it seriously.
A9 and A2Z are providing software and/or services to Amazon.com which Amazon.com uses in its retail business. This is completely different from A9 and A2Z engaging in that business. They do not buy, sell, distribute, or ship the products Amazon.com does.
So long as Amazon.com maintains arms-length dealings with A9 and A2Z (which is trivially easy for any company with semi-competent legal counsel to accomplish), the ownership of A9 and A2Z is irrelevant to Amazon.com's dealings with California.