As a devil's advocate, why do you trust the AI companies to behave as you suggest and not the other way? You say you have multitude of reasons, but list none. We have already seen by example that the AI companies do not care about laws and will circumvent societal norms as long as they get a leg up, so it's not a stretch to think they'd do things like this too.

It isn't just out of the kindness of their hearts that they don't do this. There are laws and regulations. There is also legal risk and reputation. I have to go through a legal and privacy process at my big corp job whenever I want to record a new timestamp and I need to ensure that the data is used appropriately and that it is wiped later. I've only seen these compliance requirements become more onerous over the past ten years and I expect that to continue.