Year round fair weather means that roads last longer without maintenance and perform better. If there were frost heaves and common storms to worry about then road maintenance would be a bigger issue, but as it is the condition of the roads matters less and so it gets less attention. The statistics are also skewed by extreme outliers like Oakland which have an unusually large number of unusually broad streets which naturally leads to an unusually large maintenance problem. Any rational person could see that, but road maintenance is not something most Americans relate to rationally.