XA:
It is supply and demand
If by that you mean monopolies can charge what they like, then yes, I agree. But there will come a point when there will be no demand, then they can stop supplying. And I think that is their ultimate goal. Light aircraft pilots don't put their cars in the long term car park for two weeks and don't go near any of the shops in the terminal, so they don't tick any of the accountants' boxes. Interestingly, business jets don't either, so you'll find BAA airports rather half-hearted about providing facilities for them. I believe it costs about £1000 a go to land a bizjet at the likes of Stansted, London City etc.
NS