At the risk of re-entering the debate over this fairy tale of the 'runaway Spyder', some points certainly go unanswered/unexplained:
IF, as might be possible, the dad simply left the Spyder running, unattended, in gear, with parking brake on, and left the scene even momentarily (an action which, I believe, most folks would consider careless, perhaps even rather negligent) ... and IF an unaccompanied 3-year old managed to climb aboard unaided (questionable) and get herself into a position where she could (a) - reach far left and figure out how to release the brake, and (b), then reach far right and have enough strength in her small hand to twist the throttle hard enough to get the bike up to speed (somewhat dubious)... that's the least problematic of this improbable concoction of an explanation ...
IF, as some suspect, he left the Spyder running, unattended, in gear with parking brake on, and walked momentarily away while leaving a 3-year child already aboard awaiting his return, there's a fair chance most folks would regard that scenario not simply as carelessness or basic negligence, but more as gross negligence... a case of recklessly creating a situation of danger to a child who has no proper basis for appreciating the risks of 'playing around' with the buttons and switches on a powerful, fully operational machine, but every likelihood of wanting, or being expected, to do so. If that's the story, the guy just dug himself deeper into the quicksand.
BUT, even if either of those scenarios did cause this calamity to take place, THEN it seems the kid roared off ALONE on the Spyder, leaving dad to chase the moving bike down the street, all the while catching up and jumping on (like some kind of trick rider with a circus pony). Really??? Maybe the guy is a track star sprinter (he caught up to a speeding Spyder!!); he certainly has more agility than brains (he managed to vault himself through the air and land in the pillion seat of a moving motorcycle). But, not quite adept enough to prevent either his child or himself from falling off. By the grace of someone, no serious injuries. Except to the Spyder, still running, in gear, once again unattended, now with no brake on, and careening madly onward to its demise.
Impossible??? perhaps not.
Highly improbable??? absolutely, IMHO.
The 'story' I'll believe is the one that holds that dad was showing off, with the kid astride the gas tank. He takes his hands off the bars and suggests that she 'drive'. She twists the throttle. The Spyder lurches forward, bucks them both off, and crashes. Just a tad more probable. But what do I know... although I've been bucked off both horses and bikes a few times, and even a car once.