If I were implementing one of these black boxes, I'd interpret "reasonable" in a privacy-preserving way: use a ring buffer that stores, say, 4 minutes of data,

If I were implementing one of these black boxes, I'd interpret "reasonable" in a privacy-preserving way: use a ring buffer that stores, say, 4 minutes of data, and stop recording 2 minutes after a crash is detected. That should provide enough data about the crash without being useful to someone who wants to spy on the driver.