The situation these days is that low cost airlines don't usually pay the advertised airport charges, or anything ike them. Smaller regional airports in particular can only attract the Ryanairs and easyJets if they give these airlines a 'good deal'. In return the low cost airline will bring significantly increased footfall that then feeds an airport's ancillary revenue streams such as car parking and retail outlets.
The old business model for airports where airlines paid the advertised high airport charges (from which an airport made most of its profit, it if made a profit at all) led to few flights at many smaller airports and those that did operate charged very high fares.
The low-cost airline 'revolution' has brought airline travel in reach of vastly many more people than was the case in the past. Fares are down but frequencies and the number of destinations up. So that an airport can operate viably whilst receiving much less revenue from airlines it charges more for such things as car parking and drop-off (in many cases). Some also charge for fast-track security and luggage trolley use.
Taken as a whole package, passengers still pay considerably less to fly from A to B than they would have done years ago when car parking was relatively cheap and drop-off charges were unknown. The alternative is to return to the pre-low cost airline days when a lot of smaller airports struggled because of the few flights with high fares.
I'll give you an example. My local airport is Bristol (BRS) and I've been using it for the past five decades. In the early days of my patronage it handled fewer than 300,000 passengers a year, had very few scheduled routes and those that did operate were very expensive. In the 80s a return trip to Glasgow/Edinburgh was at least £150 - at 1980s prices - but the schedule was appalling. BRS was then city council-owned and a loss-making drain on the rate payers' purse. From memory, car parking was cheap though - for the few people who were able to fly from there.
Nowadays, BRS is arguably the most successful of the smaller UK airports (say those handling under ten million passengers a year) with a current annual throughput of nearly 9 million. It's also a profitable airport for its owners these days.
However, a cursory look at its balance sheet for 2018 shows how important non-aeronautical revenue is to its successful operation.
Overall revenue £112 million
Aeronautical revenue £42 million
Car parking revenue £35.6 million
Concessions (retail etc) revenue £31.1 million
Other revenue £3.3 million
I'd rather have to pay 'through the nose' for car parking and have a choice of up to five return flights to both GLA and EDI each day at under £60 return at 2019 prices than go back to the old business model where I'd have to pay £150 at 1980s prices for the very few flights that operated to Scotland.
I have no interest to declare as I've never worked in the aviation or travel industry, nor in retail for that matter.