Muggings in similar to the ones described in the Snatch Theft story are very common in South Africa in general. Women are especially targeted. Having grown up in South Africa, it becomes second nature to always be conscious of preventing this kind of thing from happening.
I had my handbag stolen when I was approached by a guy with a knife while I was walking home from a night of dancing and having a few drinks with friends. In hindsight, I should never have been walking home at night (always uber or catch a taxi) or carrying a handbag which made me a target.
I suggest that you avoid carrying a handbag if you can when out and about at night in Cape Town in places like long street and Bree street or, alternatively, wear your handbag with the long strap across your chest, making it difficult to steal.