No you are incorrect. The airline ride at cost does NOT have zero book value.

The book value cost for the airline seat is the cost of operating the aircraft - which is fuel, depreciation, maintenance, labour, and airport fees - divided by the number of seats.

If the business class seats are different, then there may be a different formula for calculating the cost - for example seat volume based (for base fare) plus the added cost of the average service level - like the champagne or "free" meal.

In fact, even the airline may sell the same seats for vastly different prices, on the same route.

The passengers on that plane will pay HST, for example, on their individual price, not on the "average price". 

The "average price" would be the fair market value, whereas book value is the individual transaction amount.

It is self evident the tax system, is based on the transaction price and not the average or "fair market price".