Just another trick to make the overall ticket price 'look' cheaper to begin with.
no different to Banks presenting a cheaper interest rate, but then the fees when taken into account could mean the rate is actually higher than average,
Or super funds presenting high returns to make you think they are better than average, but then the fees could mean that this fund is actually a worse investment than average!
It is the similar idea going on with Ebay when you think something is cheaper, until you see the freight charges, and the competitor is more expensive but offering free freight, and therefore is in reality is the cheaper one!