Its possible because if you lower profit margins, but increase turnover by say tenfold, the airline actually stands to gain.
If currently it costs say sh20,000 to fly NRB-MSA, but you only have 20 passengers, your total is 400,000.
But if you lower the cost to say sh5,000 and you now have 100 passengers, your total is now sh500,000. If you then have numerous flights, lets say 10 flights per day, you actually make more profit because people who never flew will now be interested coz of cheaper prices, so even though you have reduced your per flight prices, you have substantially increased your turnover which eventually translates to bigger profits. Thats why Southwest airlines is able to charge very low prices, but the downside is expect crappy service and even stopovers to refuel, like the author said it will literally be a matatu hopper. Then when the other competitors try to steal these new customers, they will have to lower their prices, a price war will ensue causing the predicted sh2,000 flight to become reality.