Africa is where tours have the Strongest case, has public transport and infrastructure are very limited. Making the continent, in general, a difficult place to have a solo adventure (while it might be achievable in South Africa). At the same, the aviation market is underdeveloped, and lacking low-cost airlines, making flying expensive. With so many natural wonders to visit, landscapes to see, and big game to spot, tours are the perfect way to see the continent. They also take the hassle out of those pesky border crossings.