>How so?

Because Google Research and DeepMind are world-leading research laboratories. This is universally understood by everyone who works in machine learning.

>What has google done that's open source or are we supposed to take their word for it

I can see you have no idea what open source even means. Name three great open source things that OpenAI has done. No googling.

>Research papers that are "peer reviewed" don't count for obvious reasons

Oh, like the transformer architecture that everybody uses? ChatGPT and the DALL-E series would not exist if it weren't for Google Research. How about Chain of Thought prompting? What about instruction tuning, Mixture-of-Denoisers and LAMBADA? Chinchilla scaling laws? Socratic models? AlphaFold, AlphaTensor and DreamerV3? So on and so forth.

I haven't even mentioned any of their SOTA language/image models.