Ask HN: Should professional data be signed?

I would like to propose that every frame of production-grade material should be signed. Every frame from a photojournalist's camera should be signed. Every frame from an speaker, journalist, author microphone or pick-up should be signed. This has been done at the high end from the beginning: doctors sign their notes, engineers sign their drawings, artists sign their paintings. Developers now sign their code. And it's possible that content that's being put out with the assertion that society should pay your for it, should be signed as close to the sensor as possible. Every manipulation should be signed. And the whole network of signatures should be traceable. Ultimately, we're going to need this. What I'm not talking about is your personal iPhone's pictures. The bar to entry to society should be low. The bar to entry in the professions should be high. Ideally, the browser should show a broken lock whenever the page you're reading has broken content, that is, content where the chain of signatures accumulated in production has been broken, or is backed by a root certificate you don't trust. Let's take lab results. A variety of Congressional laws establish some inspection regimes over labs that produce data for human medical treatment. Should not the FDA sign a de novo or 510(k) certificate for the manufacturer? And then the manufacturer signs the machine as an intermediary. Medical societies and the state licensing boards similarly sign for the pathologists that run the labs. The pathologist running the lab, receiving the machine, should then countersign the certificate that machine uses to sign further intermediaries for regular QA periods. As QA processes are performed, the governing body (FDA, CAP, etc) can countersign as survey results are entered and pass. Then the machine, which passed QC within the last 24 hours (signed for by an authorized tech) signs the results. So you have confidence all the way to the result of who did what, from the original scientific paper to the result for the patient in the ER. In my mind this seems obvious. Why isn't it done already?