On any trip into the Karoo or less light polluted areas of rural South Africa one can, weather permitting, do some stargazing if one wishes to. So if any trip into the country can also have an astronomy flavour, why have specific astronomy tours?
It is a question of where the main focus of the tour lies. On astronomy tours the main focus will be on astronomy, stargazing and various astronomy related activities with other non-astronomical things happening on the periphery. On all the other tours, astronomy and stargazing, if they happen at all, will be the items on the periphery.