The same trip can cost less with a change of plane than without one, even though it uses more fuel, more crew hours and more of the traveller's day. Airline pricing responds to competition and capacity rather than to distance.
Nonstop routes usually have fewer competitors
A direct flight between two cities exists because enough demand supports it, and often only one or two carriers operate it.
Limited competition on that pair allows a higher fare. Meanwhile, several airlines can offer a connecting version of the same journey through their respective hubs.
The connecting market is therefore contested by more sellers, and contested markets price lower.
Connecting passengers fill seats that would otherwise fly empty
A hub airline schedules flights primarily to serve its own network, and each aircraft leaves with seats unsold by local demand alone.
Selling those seats to someone travelling through adds revenue against costs the airline has already committed to.
Any fare above the marginal cost of carrying one more passenger improves the outcome, which is why connecting inventory is discounted aggressively.
Travellers are sorted by what they will pay for time
Airlines price to separate customers by willingness to pay, and time is the cleanest way to do it.
A business traveller on a fixed schedule values the nonstop and will pay for it. A leisure traveller with flexible days will accept a stop to save money.
Offering both products at different prices captures revenue from each group that a single fare would lose.
The hub carries real costs of its own
Connections are not free to operate. Bags must be transferred, aircraft must arrive in coordinated banks, and staffing at the hub must handle concentrated peaks.
Delays also propagate, since one late arrival can strand passengers on multiple onward flights.
Airlines accept this because the hub structure lets one aircraft serve many city pairs, which is what makes thin routes viable at all.
The saving comes with an exposure
A connecting itinerary sold as one ticket obliges the airline to rebook a passenger who misses the second leg. Two separately purchased tickets carry no such protection.
The cheaper fare is therefore also the one with more failure points, and the size of the discount tends to track how inconvenient the routing is.
A long layover, an early departure or a connection through a congested airport all widen the gap, because each is a form of discomfort the airline is paying the traveller to accept.
When a nonstop and a connection are priced the same, it usually means the direct route has picked up a second operator.