The Assessor's Office has nothing to do with the total amount of taxes collected. The assessor's primary responsibility is to find the fair market value of your property, so that you may pay only your fair share of the taxes.
Amount of Taxes
The amount of taxes you pay is determined by a tax rate applied to your property's assessed value. The tax rate is determined by all the taxing agencies-city or county, school districts, and others-and depends on what is needed to provide all the services you enjoy.
The assessor's office also keeps track of ownership changes, maintains maps of parcel boundaries, keeps descriptions of buildings and property characteristics up to date, keeps track of individuals and properties eligible for exemptions and other forms of property tax relief, and most important, analyzes trends in sales prices, construction costs, and rents to estimates the value of all assessable property.
All this must be done economically (less than 1/10) the cost of hiring someone to appraise your property.