Which can be paid for on a $12.6 billion yearly budget (if it is wise to do so is another question).

Well, the budget in 2009 was $6.5 billion. It seems the taxes are growing for SF at a very high rate, and it would eventually become unsustainable. The taxes are certainly going up faster than population and inflation combined, and it sure seems like we're getting less for more money.

I think the reasons are very different though. For small towns it seems to be poor planning, for larger cities it seems to be corruption.

Not sure a $1B street update (literally 2 miles of street in a city with thousands of miles) could be regarded as "affordable" with a $12.6B city budget.