A lot of bus companies use that sort of system now, a big driving force being fuel economy, as well as safety, passenger comfort and reliability. I suppose if a driver is pulled up for bad driving, or looses out on a bonus for good driving (many companies use a carrot and stick approach) because the next driver has not logged on to the system properly, then it should be a fairly simple matter to prove that they were not driving at the time, afterall drivers will be rostered to particular duties, and there is also the "how could I be driving that bus like a maniac at that time when I was also driving that bus perfectly sensibly at the same time, and if you believe that is the case then I want double pay for that period!"