Rather than encrypting 'our' data, we could also strive to make 'their' data as accessible to us as our's is to them. Aka transparency.

I think that's a failing strategy. You can only trust that 'their' data is open as much as you trust 'them'.

This is the robustness principle (for API design/use ) applied. "Be lenient in what you accept from others, stringent in what you emit."

As applied to this case, it's "Be lenient in what you you expect reality is, but stringent in what you attempt to shift reality to."