There is so much free space in British jails that the Government wants to fill them with mobile phone users. Not to mention people who have been involved in car accidents - even if the only "victims" were their own children, travelling with them.
Motorists are well incentivised to drive carefully because - even with modern safety aids - they occupy the most dangerous seat in the car. What sane person would infer criminal intent on the part of someone who has killed or injured his or her own child by careless driving? What happened to "Accidents will happen?" or to "There, but for the Grace of God, go I."
But then, for Labour, driving a car (as opposed to being driven in one by a Government employee) is quite sufficient evidence of criminality.