Low cost model needs subsided airport fees, liberalized airspace and customers ready to pay all the ancillary revenue stuff on board.
In Europe, there are many regional airports where left-leaning goverements find it a great idea to use taxpayer money to subside low cost airline operations. Once the airline has discounts in its hands, it can fly to any european destination it wishes. On board many customers will happily pay extra for coffee and snacks "since the ticket was so cheap".
Meanwhile in Africa, Stelios will get laughed out from any meeting where he would try to get discounts. He will also find out that protectionism is still firmly in place, even in countries where the national airline has collapsed. And most customers will stiffly avoid paying any extra fees (apart from overweight luggage...)
But, Stelios/Fastjet team must already know the above, and yet still plan to enter the market.
