Look at the source of funds. The most recent county budget doesn't seem to supporting your arguement. It doesn't look like funding for roads is coming out of the general fund. The funding sources for street and road maintence is found on page H-204 here.
http://www.budget.saccounty.net/cosw...sac_017550.pdf
The primary source of funds is something the county calls the Road Fund. The source of funding for the Road Funding is explained here on pg 9 as money coming from gas taxes.
http://www.budget.saccounty.net/cosw...sac_018324.pdf