5) Understand ML; concerned - "Why do other people in the ML industry think it's OK to use and store peoples data in without informed consent (which are only those in group 3, and group 1+2 don't have informed consent)"
Group 5 is "We must be ethical, can we still collect training data"
Different priorities, different outcomes.
If training data can't be collected ethically, do you think group 4 still would, or something? That just seems like trying to out yourself on an ethical high horse without a real distinction in action.
That is: Group 4 would be more willing to compromise ethics if absolutely necessary to get the data said group needs, while Group 5 would be more willing to compromise data collection if there's no ethical way to collect that data.