Ironically all of this could be achieved with a negligent homicide prosecution and sentencing guidelines.
For example, negligent homicide by cycling on the pavement would carry a higher tariff than negligent homicide by cycling on the road, as in the case of Rhiannon Bennett.
Negligent homicide behind the wheel of a motor vehicle would automatically carry a tougher sentence to reflect the fact that we need drivers to take proportionate care given the amount of people they kill and injure. For the hundreds of pedestrians killed by drivers who mount the kerb, for example, that would be an exacerbating factor relative to hitting them on the road (if they were playing chicken after beers in the park).
And so on, and so on.
It's just such a non problem. "During the 3-year period 1998-2000 out of a total of 2,630 pedestrians killed on the roads, 185 were killed by vehicles on footways. Of these 185, one was killed by a bicycle and the remaining 184 were killed by motor vehicles."