In Scotland, the total number of careless driving offences has been falling steadily from 16,774 recorded by the police in 1995 to just 8,506 in 2009-10. Maybe the extent of carelessness is falling. Doubt it.
In 1995, 43% were proceeded against in court. By 2009-10 it was down to 39%. Most of them are already dealt with by a fine and endorsement. Only 500 of the 3,509 resulted in a disqualification. The average fine was £249.
Causing death by careless driving doesn't seem to have resulted in fewer causing death by dangerous driving charges. In the two years it's been available (2008-9 and 2009-10 where there's data). There wasn't a noticeable drop (the numbers fluctuate a lot year to year).
Turning this into something dealt with by the police with a fixed penalty notice would probably lead to more people being charged / issued with an FPN. Does it not say that the FPN would involve endorsement. Bizarre if it doesn't when speeding does.