A guided tour uses expert help
The world is an awfully big place.
There are language and cultural differences which are far better explained by a local guide.
A back up vehicle allows not only carriage of your luggage, but a place to store that other camera, sit in, if you fancy a break, or carrying that particularly large stack of bananas that have been bought from a street side vendor.
In short a guide and back up vehicle is a great option
I offer 1-2 trips of this type ever year