Well John, if ya want my theory here, that might be because of the car tire's squared-off profile. I mean look at Ed's picture No.1 up there again and how it seems as the guy is riding the edge of the tire(with once again much less tire contact patch as he does it) how it appears the height of the bike's rear end seems to rise just a bit. And thus, because of the increased height of the rear end, that would make for a little more ground clearance before you'd start scraping the pegs or floor boards.
(...that would be of course JUST before the bike's rear tire looses all grip on the road and ya end up low-sidin' the sucker as the contact patch reaches the sidewall of that FREAKING CAR TIRE!!!)
