Basic economy sits in the same cabin, in the same seats, with restrictions attached. The restrictions are the product, and they exist to solve a pricing problem rather than a service one.
The fare defends against low-cost competitors
Search results are sorted by price, and an airline whose lowest fare is higher than a competitor's disappears from the top of the list regardless of what it offers.
Creating a stripped fare puts a competitive number on the screen for routes where low-cost carriers operate.
The airline is not trying to sell many of these tickets so much as remain visible in the comparison that decides where the shopper looks first.
Restrictions stop existing customers moving down
The risk of a cheap fare is that passengers who would have paid more simply buy it, which reduces revenue without adding a single passenger.
Restrictions solve this by making the fare genuinely unattractive to anyone with a preference about seating, luggage or the ability to change plans.
The rules therefore target exactly the things a business or family traveller cannot do without, which is why they can feel deliberately awkward.
Unbundling converts service into revenue
Once seat selection, carry-on allowance, changes and boarding position are separated from the fare, each can be sold individually.
Ancillary revenue of this kind carries high margins and is not always subject to the same taxes and commissions as the base fare.
The final total for a passenger who buys back the removed elements often exceeds the standard economy fare, which is a designed outcome rather than an accident.
The upsell is the point of the display
Booking flows present basic economy alongside the standard fare with the differences listed in full, at the moment of decision.
Framed that way, the standard fare reads as good value, and a substantial share of shoppers move up having arrived for the cheaper one.
The basic fare earns its place by improving sales of the fare above it, even on routes where few passengers actually choose it.
When the cheap fare is the right one
For a short trip with a personal item, fixed dates and no preference about seating, the restrictions cost nothing and the fare is straightforwardly cheaper.
For anything involving luggage, a companion or a chance of changing plans, the add-ons usually erase the difference and often exceed it.
The comparison worth making is the full total including everything that will actually be needed, which is the number the display is arranged not to show first.