There is an event in Tokushima that has the same requirement. As Honoluljoe pointed out, I can understand why they do it, but for me, the deciding factor is entry fee. If its a local event run at no cost, then not wanting to support people with problems is fine, but if it is a revenue chasing event, then a van or two picking up stragglers is the least i would expect. A quick look at the site and a quick calculation reveals that if they fill all the available slots, they would be looking at 27 million yen in revenue, less relevant fees of course. With that much income, they could afford to run a whole fleet. I hope the rest stops provide sit down 5-course meals.
As for checks at the event, there is one Shikoku hill climb event that has 2 mechanics give all the bikes a once over, that literally takes 30 secs as the Directeur mentioned.