Why is the air bag module sometimes called the 'black box' ?

There are several possible origins of the term 'black box'. Some believe it is because early (flight data) recorders and WWII radar units were painted black, while others think it refers to the charring that occurs in post-accident fires. Yet another description is, "the term ‘black box’ has been used to describe something that performs a function, but its inner-workings are complex and mysterious." In media related stories, CNN uses the term black box to descibe the air bag module crash data "due to a lack of a better term."

AIR BAG SDM / BLACK BOX / CRASH DATA AVAILABLE (depending on year and model)

Vehicle speed (in five one-second intervals preceding impact)
Engine speed (in five one-second intervals preceding impact)
Brake status (in five one-second intervals preceding impact)
Throttle position (in five one-second intervals preceding impact)
Driver's seat belt state (On/Off)
Passenger's airbag enabled or disabled state (On/Off)
Airbag Warning Lamp status (On/Off)
Time from vehicle impact to airbag deployment
Maximum Delta-V ( DV ) for near-deployment event
Delta-V ( DV ) vs. time for frontal airbag deployment event
Time from vehicle impact to time of maximum Delta-V ( DV )
Time between near-deploy and deploy event (if within 5 seconds)

What’s more, the ABM records engine rpm, throttle position, and whether the driver is applying the brakes, even though these parameters have nothing to do with the deployment of the airbag. Furthermore, the system records these parameters every second, along with the vehicle speed, and remembers the last five data points.

Therefore, if you have a crash in which the ABM thinks about deploying the airbags - even if it doesn't - the airbag module records onto a memory chip the values for these parameters at the time of impact and for the previous five seconds.
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I suspect few owners have any idea these data are being captured. And it’s not a difficult task to retrieve them. For $2495, Vetronix Corporation will sell you a crash-data-retrieval system that can transfer the recorded information from the ABM to a PC. What is unclear is who owns these data and who has the right to read them.
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So the question arises: Can an owner erase the data before they can be downloaded? There are certainly ways of clearing a memory chip, or the vehicle’s owner could simply destroy or discard the ABM. But lawyer Peters advises against this move: "During a trial, the presumption is that lost evidence goes against the guy who lost it."

So, not only do most Americans have no idea their cars may be recording their driving behavior, but there’s also little they can do about it. And think about this: Current ABMs record just five seconds of data before a crash, but computer memory is dirt cheap. For very little cost, that recording time could be extended to five minutes—or five hours!
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I find this march of technology, unrestrained by any laws or even public discussion, very disturbing. Not surprisingly, so does the American Civil Liberties Union.
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We need to discuss these issues soon, before our cars are programmed to transmit their speeds to traffic cops using the Wi-Fi technology that will quickly be available for pennies per car.