My Osteo is a youngish Male and well travelled, he frequently disappears off for a couple of months of travelling and that was his experience of S. Africa. It's safe only if you take extreme care. When he stood outside the Hotel waiting for his cab (as is pretty normal behaviour) He was told to go back in and wait inside until the cab showed up as there was a risk of kidnapping. My Son went a few years ago with his School and it wasn't like that at all. The situation is deteriorating and caution is needed at all times. Caution somewhere like Rome where you get pickpocketed is one thing, having to be cautious because there is a risk of kidnapping is a whole different level. He spent 2 months travelling through Colombia and didn't experience anything like that.
i would really love to know what part! as i said above, my sister was a solo traveller there and drove herself also - and felt fine about it. there are iffy spots (as with anywhere) and she was recommended to avoid townships and got a lot of warnings about pretoria in particular but she’s a seasoned traveller and it was really no different to going anywhere (like going to a city in the us and being told the no go areas). my parents also go very frequently, again seasoned travellers, and said the same.
to be told not to stand outside your hotel or someone will kidnap you is something i would only expect from an extremely hostile and dangerous environment. i can’t see that was the case in cape town (as an example) which still has a large tourist population from all over. serious crimes on tourists are also extremely rare in most places because the criminals just don’t want to get involved with the embassies or international police forces.
it is relative though i guess! i’ve been all over, in particular the us, and the only place i truly felt unsafe was new orleans. my sister has been all over the world and the only place she truly felt unsafe was egypt. yet other people have told me the exact opposite about both these places!