Massive difference in flight prices - Airlink

Travelstart quotes a return flight from jhb to Cape Town at R2230. A return flight on the same airline on the same dates from Mthata to Jhb is quoted at R5444. How is it even possible that one flight costs 140 percent more than the other. Flights from Mtata are mostly fully booked. So seat occupation is not a factor. This smells like unfair profiteering