They already do that, there’s all kinds of XML and JSON and whatnot standards to communicate product info, inventory, whatnot. The reason Google is doing this is because this information cannot be trusted all the time, there will always be bad actors.

The process may eventually evolve in a cat-and-mouse game, where malicious e-commerce sites try to detect these Google crawlers and serve different price info to them, but let’s hope it doesn’t get this far.