Yes, good point. But it all depends on level of risk, type and amount of data etc.

You don't need any electronics for a film camera. Or any metal, for that matter. It's a risk to take such an item in, but maybe it's worth it for your use case.

And I guess if it's small amounts of text, there's always human memory (or writing on your skin?).

So you are (obviously I guess) trusting the people accessing the data to not abuse it, "helping" that trust with whatever technical countermeasures make it harder to move bulk data.