It is important to understand the fundamental differences between the landing fees of airports in Great Britain versus Detroit Metropolitan. In Great Britain,airlines pay a fixed fee for landing based on the time of day and the number of passengers. Airports also collect rent for terminal space from the airlines, concessions, parking and other activities. The total revenue for the airports is a function of the amount of total activity. Total revenue is not contractually limited, as it is in Detroit, so revenue cannot exceed costs.
At Heathrow Airport, BAA charges the following fees for landing:
(1A) £290 ($493) per aircraft between 7:00 AM and 9:59 AM and between 5:00 PM and 7:59 PM or
(1B) £175 ($297.50) for all other times, plus
(2A) £5.50 ($9.35) for each departing domestic passenger during peak periods,
(2B) £11.05 ($18.79) for each departing international passenger during peak hours and the summer travel season. There is no per passenger charge for international passengers during the less busy winter travel months. 
These fees apply to all fixed-wing aircraft. Thus, if a business jet with four people aboard chooses to land during peak hours, it will pay the same landing charge as a fully-loaded Boeing 747 plus charges for each passenger.
BAA has a slightly different fee schedule for Gatwick airport. In general, the fees are slightly lower and sensitive to aircraft weight. With these fee schedules, BAA accomplishes many different goals:
Generating more revenue by increasing landing fees during high demand periods when international flights are arriving from the Western hemisphere.
Encourage use of Gatwick airport over Heathrow to reflect Gatwick's lower demand and surplus capacity.
Encourage winter travel to England through lower passenger charges during off-peak seasons.
Discourage airport usage by small aircraft by the very high landing fees. General aviation is encouraged to use other, less congested, airports.
Maximizing revenue by encouraging the use of larger aircraft through the airport fee structure. Since small aircraft use approximately the same amount of resources but generate less revenue than aircraft with more passengers, the airport benefits from the use of larger aircraft. 
All of these above goals can be achieved with a flexible pricing structure used by British Airports Authority and allowed by the British government. Under the existing agreement, Detroit Metro has no such opportunity for pricing variability. Price is established by landed weight after all other airport revenue is determined.
Using a system such as that employed in Great Britain which shapes and is shaped by market pressures through pricing policy, Metro might be able to accomplish some of the following goals:
Discourage airlines from scheduling more departures than the system can handle in peak demand hours by raising the price during those hours.
Encourage the use of large jets during peak hours to reduce the number of flights while maintaining the number of available seats.
Improve safety by discouraging the use of Metro's facilities by general aviation aircraft by charging a fixed rate for each aircraft rather than a weight-based rate.
Encourage or discourage the use of Detroit as a hub airport by making fees either lower or higher to attract a different number of flights.
Set the amount existing and prospective airlines using Metro will be charged – regardless of the amount of airport activity.