A journey with a change of aircraft frequently costs less than the nonstop covering the same two cities. The gap reflects how airlines fill aircraft rather than any difference in distance.
Nonstop seats face weaker competition
On many city pairs only one or two carriers fly nonstop, and those seats are the ones business travellers will pay a premium to secure.
Everyone routing through a hub is competing for the same passenger with an inferior product, so they discount to compensate for the extra hours.
The price difference is therefore a payment for time. The nonstop is priced against what its convenience is worth, not against what the flight costs to operate.
Connections fill seats that would fly empty
A flight from a hub to a smaller city has to depart whether or not local demand fills it, and local demand rarely does on its own.
Connecting passengers are the difference between that aircraft leaving full and leaving half empty. Their marginal contribution is worth taking at a low fare.
This is why the discount grows as the endpoints get smaller. The thinner the local market, the more the airline needs traffic flowed in from elsewhere.
Hub economics reward volume over margin
A hub works by combining many small flows into a few large ones, which is what makes a long route viable when no single city could support it.
The system depends on banks of arrivals and departures scheduled to connect, and every seat sold across that bank improves the return on the whole structure.
Pricing follows accordingly. The airline is optimising the network rather than each flight, so individual legs can be sold below what they would fetch standing alone.
The traveller pays in time and exposure
The cost of the cheaper itinerary is hours and risk. A missed connection converts a saving into an overnight stay, and tight layovers make that outcome more likely.
Where the whole journey sits on one ticket the airline carries the rebooking obligation. Separate tickets shift that obligation entirely onto the passenger.
This distinction matters more than the layover length. A generous connection on two separate tickets is often riskier than a short one on a single booking.
Where the discount disappears
On dense routes between major cities the nonstop can be the cheapest option, because competition among nonstop carriers is already intense.
The connection also loses its advantage when the hub is congested, since delay risk is priced into the traveller's calculation even when it is not priced into the fare.
As a rule the saving is largest exactly where the inconvenience is largest, which is the trade the fare structure is designed to make explicit.