I would not disagree with your basic thinking, but things have to be equal in all areas and they never have been between cars and bikes.
Some sad rich kid can pass his test and get straight into his dad's M3 take his mates and girlfiriends out for a run, start raciing with somebody and stuff it into a tree killing a car load, no apprenticeship there! Then again I have known a few who have served an apprenticeship by smashing a few cars up before finally killing a car load of mates.
A lot of leisure bikers would take a bloody long time to do the 20,000 mile two stage apprenticeship and may have given up bikes whilst waiting.
In any case, does speed and performance really make all that much difference. Even though I agree with the sentiment, and forgetting my earlier comments, it does seems to me that a lot more young drivers get killed or injured in 1.2 Corsas than Subaru Imprezas. Similarly a lot more youngish kids get killed or injured on scooters or mopeds than larger bikes.
As has been mentioned, everything is about experience really, like the young football apprentice, running around in a small cheap run around, signs a big money contract in has late teens, then just has to have an Aston, even if he doesn't like cars that much and can't really drive.
If we have to have progression we also need something to progress with!
Now we are getting a few decent 250s coming back, I think we should be letting people ride these with L plates and they might keep them a bit longer after passing their tests, (nobody wants to stay on a 125), then maybe something like a non supersporst 600, (new Divvi, SV 650, Bandit, CBF600 or CB600F etc.).
The other issue is riders coming back after years off bikes then joining a group of mates and deciding they just have to start off with a Fireblade, or they would not have any street cred.
Then again, in my days you could go straight to a Jap 250 with L plates, and lets face it, they were often as fast as Brit 500s and not much slower from the
big Brit 650s !!
However, a lot of kids got killed on X7s, RD250s and the like and that's why we are where we are now.
