hey mark,
my predominant issue with this one is that the cars that we all like to buy (GTRs, GTSts, Supras, Silvias) are often bought by people just like us - motor heads - in Japan.
If i had my car in japan i'd take it out driving everywhere too...
I do agree with you that it's too hard for the average user to drive in Japan - the times I've been there i've only even got in a taxi a few times! - but for the enthusiast with these turbo play cars, they'd go out and use them.
even if we assume that people won't do as many kms, there are still a few too many 12 year old GTSts and GTRs that have done 88,000kms for my liking... just a look through the classifieds on this site will give you heaps of "original low km first time registered in Australia barnyard find" cars...