Hi,
I'm guessing that's LAS? Handling agents at most commercial airports are generally pretty steep, that is true. Departing passenger fee does sound a bit like a way of screwing you for a bit of extra cash in the case of a simple small aircraft/one passenger movement. Not sure if this is an airport or FBO charge? If it's the FBO, I guess if you were to try to justify such a fee, an FBO such as LAS is geared up for bizjet-type handling where if there are a number of passengers it can significantly increase the workload for the handlers (multiple vehicles for pax transport, escorting personal cars on and off the apron, luggage handling, taking pax through immigration etc. where required for international flights). Defining a one-size-fits-all pricing structure can therefore be tricky; every movement is different. A fee-per-passenger is, I suppose, a compromise. Also bear in mind that although all you may require is to park, use the loo, pick up passenger and go, a lot of the handling agent's customers are a lot more demanding - fuel, hotel bookings, 'interesting' catering requests, de-icing, toilet servicing, forklifts, ground power, freight handling, chauffeur/coach bookings... Ok, these may be have their own associated charges, but it's ultimately the same small team who will be responsible for co-ordinating the whole affair.
In LAS's defence, having sampled most agents around the UK, I'd probably say their prices are comparable for the type of operation/airport in question. I'd also make a point of saying that they are one of the very very few who will invariably offer to give you a lift straight from the aircraft to the hotel and back (assuming it's reasonably local), or out to the shop/restaurant/terminal etc. to grab a bite to eat, without whacking an extra charge on the bill. Ok, it may seem a small gesture but if it saves you £15 in a taxi which is quite often the only option then it will go some way to recoup some of the fee.
Having said that, I know that certainly at one point it was possible to ask one of the flying schools for handling - Helicentre rings a bell? That may work out as a cheaper option but I'm not sure what exactly they will provide - I guess this may be the most suitable option if you are a light GA type and don't require much looking after. Worth a phone call at least if it saves a few quid.
Hope that's of use?
A38