This generalization is so broad as to be useless (akin to "America is a racist, xenophobic place"). Africa is 54 countries and 1 billion people and countless cities and neighorhoods, painting with a broad brush is unhelpful. Only a handful of countries have active conflicts or instability, it is easy to avoid them on a trip such as this one.
[Edit] Here's a fun game that was featured on the Daily Show: see if you can you tell if a photograph was taken in Africa or the US[1]
Africa is really, really huge - it has almost 4 times the landmass of the contiguous US. Avoiding specific locales is pretty easy.
Can you enumerate the dangers that the two friends will face in Africa - sudden malnutrition? If you are referring to armed conflict or the danger of being abducted by the local African warlord[1], then you might be happy to know that such dangers are highly localized and the high-risk areas easily avoided; after all, Africa is a large place (larger than the US, China and most of Europe. Combined[2].
1. Common trope
2. http://io9.gizmodo.com/africas-true-size-will-blow-you-away-...
https://www.roadscholar.org/find-an-adventure/21421/circumna...
A normal clean toilet is no danger, same as everywhere else in the world, but if you're going to the loo in one of those ramshackle open-to-the-elements rustic outhouses, you might want to check the seat.
Yes, the toxicity on paper of Australia's animals is sky-high, but that's not the full story. You're far more at risk of heatstroke than animal problems when travelling Australia.
If I really wanted to understand Africa I'd pick a city and go work and live in it... Not drive through it in an army truck.
"ain't the same fuckin' ballpark, it ain't the same league, it ain't even the same fuckin' sport."
The only major mechanical issue they had was caused by dirty diesel, and if they'd had some sort of pre-filtration setup they could have probably avoided this.
Their major issues were simply down to the weight of the vehicle and poor route selection.
This sounds like received wisdom. Is there any evidence to support it? Why would one believe that a land rover's engine requires more maintenance than the average engine found in all the aggregate "old trucks"?
The reason I made my original statement is that old, frequently ex-military trucks and old busses form the backbone of a lot of central and northern africa's transport networks, and the local mechanics are incredibly ingenious and experienced at performing "bush repairs" or fabricating spares to keep them going.
https://en.m.wikipedia.org/wiki/Toyota_War
https://en.m.wikipedia.org/wiki/Technical_(vehicle)
http://www.newsweek.com/why-rebel-groups-love-toyota-hilux-7...
The more correct way of characterising both would be that they will continue to run and function without ongoing maintenance (the proper level of which is way above a modern vehicle) until they break in a spectacular and often terminal way.
To attempt to answer your question, I think the general implication is that "old trucks" are designed for high maintenance intervals whereas Land Rovers, especially as used by the military, are designed to perform a function for short intervals with the long-term aid of a logistics chain.
I find this fascinating. To a layperson like me all combustion engines seem like they must be uniform. Thanks.
I have a 2001 Nissan Xterra that's been sitting in my driveway for almost 4 years with a blown head gasket because of the combination of lack of spare time, other available vehicles that I could drive, and the complexity of disassembling the engine to remove the heads. The seats and hatch area are now full of engine parts and I still have to finish taking off the passenger side head.
Contrast that with my 1987 Toyota pickup: I would have had the entire job done in a weekend with time to spare.
One bloke had his Citroen die in such a way in Africa... and had to rebuild it into a motorcycle to get out of where he was
http://www.dailymail.co.uk/news/article-2168061/French-elect...
https://m.thevintagenews.com/2016/05/18/emile-leray-built-wo...
Which could have been solved by using a landrover instead.
Then it's not so much fun any more.
https://www.drivesouthafrica.co.za/images/home/slides/landy-...
[1] http://www.thehighroad.org/archive/index.php/t-65646.html
The tent was on the roof so it should have been safe from most animals: