Yeah I agree with Soli, you get used to it. When I moved from Cape Town to Gauteng & Mpumalanga, I also had that constant "on the lookout" vibe going, you just don't feel as safe (for good reason I suspect).
It is strange when you go down to Cape Town or Paarl now, and you see all these houses with no security. Nevermind electric fences, they don't even have walls/fences.
I had to laught at Wyv's comment, electric fences around the electric fences. Hahahaha
The traffic in Jhb is no worse than Cape Town, I'd say. I almost never go into either's CBD, just the highways around them and it is most of the same, except the people drive faster up in Jhb than Cape Town. You'll often drive 100 or 110 in the fast lane in Cape Town, while up here you'll be doing 130 in the fast lane and moving over for someone going faster