Well, since you are such a motorsport track day-organising veteran converted, you should really understand all this, but I will spell it out for you:

Costs

The track hire is $2800 for the day. That's what we pay Mr Willmington to hire the track on a Sunday for the whole day.

$2800/17 entrants = $164

So far the SDC will make a $14 loss for each entrant.

So for your fabled $40 track day, there would need to be at least 70 entrants just to break even

Track Time

Max group size on the track at once is 6 cars.
9am-5pm 30 mins lunch break, 1 hr to allow for session changes = 6.5 hrs track time

6.5 hrs / 3 groups = 2hrs 10 mins track time each

Your $40 track day, 70 entrants makes 12 groups

6.5 hrs / 12 groups = 32 mins track time

So converted, now that you have shown your ignorance of what's really involved in organising a day, instead of pissing on everyone's parade, how about you go back to your keyboard racing and leave this thread alone.

Bert:

The liability in this case is covered by MDTC insurance cover, part of the track hire fee.