I agree with the points against the 1 passenger legislation.
There will just be a hell of a lot more cars on the road at 2/3am with two ppl in them. Especially when leaving a party etc.. with only 4 friends for example, thats already 3 cars instead of one!!
Now i don't know about everyone else, but when i was 18 (young dumb and full of cum), i couldn't think of anything funnier than a 3 lane drag down a highway at whatever speeds these 'underpowered' cars (i used to have a 1993 Pulsar Q, it might or might not have gone around 220kph on several occasions) are capable of.
Now i suppose my last point is going to be a matter of personal opinion, but a 3 lane drag against my mates was going to suggest i do plenty stupider shit than a few drongos in the back going 'stop for these chicks' or 'do a burnout'..