I read that there is only one notebook in the entire US that has the proprietary software to read and decipher the Toyota black box data. If it's true, that just boggles the mind.

That was true, but they brought in a lot more to assist in investigations a while back.

The issue is that the black boxes were not designed for this, and so it is an uncertain science still. Toyota aren't using an open architecture. The black boxes were designed only to trigger air bags, and they do save some data for a short time but it is not clear that there is enough traceability to be able to use it as evidence one way or the other. For some sensors, the black box doesn't actually record what was happening, but rather a technician seems to have to infer it. At times like these many people would just like access to fully developed event recorders such as the police have on their dashboards, but other times they get upset about the privacy issues.

Well, they need to GET the box in the first place!

The car is not owned by toyota... you can be sure that as lawsuits progress, there are intense legal battles in discovery over who gets access to the box and who does the decoding....

The owners have the boxes. What they neet is the technology to decode it. And that technology IS owned by Toyota.