I can see one advantage if they send the signal real time to the dispatcher. Instead of the loco icon on his board it will be the cab view, If he sees they are nodding off a call on the radio and a possible crash avoided. There would be a price to pay (unless it was say carbon monoxcide poisoning) but maybe not the ultimate one. Our police, Fire and ambulance all have body cams or more. Our schools have cameras in the classroom. I have had truckers who were making a delivery show the forward facing camera and ones mounted on the rear view mirrors. Its just a matter of time they can take the pictures. And to the gentleman who mentioned the liberal use of duck tape, I am sure Uncle Pete or any other railroad would treat that the same as if you were to defeat any safety appliance.