Company A pays OpenAI for their API. They use the API to generate or augment a lot of data. They own the data. They post the data on the open Internet.

Company B has the habit of scraping various pages on the Internet to train its large language models, which includes the data posted by Company A. [1]

OpenAI is undoubtedly breaking many terms of service and licenses when it uses most of the open Internet to train its models. Not to mention potential copyright violations (which do not apply to AI outputs).

[1]: This is not hypothetical BTW. In the early days of LLMs, lots of large labs accidentally and not so accidentally trained on the now famous ShareGPT dataset (outputs from ChatGPT shared on the ShareGPT website).