On paper SA is supposed to have a purchasing power parity of around -50 to -60% [1] (so, things are on average that much cheaper here than in the USA). Of course, SF is significantly more expensive than other places in the USA (although typically not more than a factor of say, 1.5 to 2x). If we add all this up, we've still only got to (at the outer edge) a factor of say 2 to 4x more expensive, not 10x. One website puts this number at around 2.6x for an SF to Johannesburg comparison [2].
The other issue is that SA has an extremely bifuricated economy (see our GINI index score), and local prices definitely also reflect this. I'm not sure to what degree the PPP measurements reflect this - I believe the PPP number is a national average, and the average prices in SA are aimed at people living close to or below the poverty line. These prices are typically not available (geographically) to your average software developer, who in SA easily falls into the (upper?) middle class category for the country. Their costs are drawn from that environment, too. Even if you choose to be frugal, the shops you find in the suburbs here are much more expensive than what the national average may be. On a similar note, appliances and high-tech goods typically tend to be along the lines of "find the item on the 'net, convert from USD to ZAR, add 10 to 20%", so we're definitely not seeing PPP-level savings there. There are also some other factors which are relatively unique to SA, such as the need for additional security (monthly payments to armed response companies, etc), growing trend (or need?) to send children to private schools, etc.
Apart from the above price factors making the PPP number unrealistic, most people here also seem to have high expectations of standards of living, e.g. expecting to buy property quite early on, driving shiny new cars, having houses which are usually > 200 m2, come with swimming pools, have large gardens which need gardeners to be hired, cleaners to be hired, etc (this is all a bit strange to me, coming from an eastern European background where we have a far lesser sense of entitlement).
So really, all I'm trying to say is, we're definitely not ~10x cheaper here, especially if you consider typical suburb shopping prices and some of our more unusual, frequently ignored costs. The high standards of living can be considered things we do to ourselves voluntarily (and as you say, sacrifices can be made there).
[1] http://en.wikipedia.org/wiki/Purchasing_power_parity
[2] http://www.numbeo.com/cost-of-living/compare_cities.jsp?coun...