> So they _are_ going to train on them, no matter how many checkboxes you tick to stop them.

It is a risk, but is it a big risk? If one of the big labs were to do this and get caught it would be suicidal due to the loss of confidence in them and the inevitable lawsuits that would follow for breach of contract. Given the AI labs are all desperately trying to paint themselves as Serious Businesses so that other Serious Businesses will pay loads of money for tokens the last thing they want is a rep for siphoning off sensitive customer data.