There was something economically wrong with your information -- if it's much cheaper to rent than own, it would mean that everybody who is running rental property in San Fransisco is losing tons of money, and would be better off selling out.
So I did a quick google search for actual rental prices in San Fransisco, and here was the first set of 10 listings:
1 Bedroom, 1 Bath = $2,950
2 Bedroom, 2 Bath = $2,600
2 Bedroom, 2 Bath = $1,700
3 Bedroom, 2 Bath = $3,300
3 Bedroom, 2 Bath = $3,800
3 Bedroom, 2 Bath = $3,500
4 Bedroom, 3 Bath = $4,800
3 Bedroom, 2 Bath = $2,400
5 Bedroom, 3 Bath = $6,000
3 Bedroom, 1 Bath = $2,950
That averages to a 3-bedroom, 2-bath house (not large by any means) at about $3400, or about twice what your article suggested a rental would go for.
But that doesn't mean you are wrong. One advantage to buying that isn't listed is that, while it might be a negative cash flow now, you have locked in your costs. Rental costs could double in the next 10 years, and home prices could double as well, but you will be paying about the same 10 years from now as you do today (of course, your real estate taxes will be higher, as will your insurance payments).
In a housing market with known falling prices, it almost never is better to buy (if the price is cheap enough, it is possible that the loss of capital doesn't outweigh the savings of rental), but who knows WHEN the housing prices are going to fall, or when they will stop.
The pundits have been predicting the real estate price collapse for 3 years now. At the moment, people in OUR area who decided not to buy 3 years ago, but to wait for the collapse to "buy cheap", are looking at spending 20-50% more for their houses than if thy had bought then.
However, I don't think I'd buy a home right now, because I'd expect a lot of people are wondering like I would be, and would be hesitant, which should drive prices down a bit.
Of course, in our particular area there are not a LOT of empty houses waiting to be purchased, and we have increasing population AND employment, so people DO have to buy houses, and the supply is not outstripping the demand as badly as other areas.
I don't expect my property taxes to drop. When housing prices went up, they lowered our RATES so the increases were under 10%, mostly. I'm pretty sure they are addicted to the money, and as prices drop they will RAISE the rates to keep the tax money flowing.
I hate property taxes, they don't reflect either the cost to the government for providing services to your house, OR the ability of you to pay for those services. I don't think you should have to pay taxes based on how much stuff you bought is worth.
A "square-footage" tax might be better, or a "residence" tax, although they also have the problem of not reflecting people's ability to pay. But a "residence" tax would also discourage large groups of unrelated adults from living in a house.
There has been an uptick in rental rates in the city of San Francisco lately, but his estimate is pretty accurate for the rest of the Bay Area. Rents aren't even close to monthly mortgage payments - usually around 50-60% as much.