Long story short: the function that shows the distance between the appraiser and the address shows approximate distances only. In order to have exact actual distances you would need a subscription to a geocoding service (Google charges $10,000 minimum per year for such a service).
The Show Appraiser Distance to Address feature uses a database of latitudes and longitudes that rely on a combination of city and zip code. This database shows the center of each combination of city and zip code, and both a city and zip code are required.
Zip codes are all different shapes and sizes, and the appraiser or the address might be in any part of the zip code. However, the function that calculates the distance only looks at the center of each city/zip code combination. For this reason, the distance shown between the appraiser and address is just an approximation and is never exact.
Getting exact distances would require a service known as geolocation. Google Maps offers free geolocation for any public web page. But because the admin area of your website is not public (it requires a login), Google’s licensing fees for what they consider to be a private implementation of Google Maps costs a minimum of $10,000 per year. We at Valued Websites assume that you would rather save that money and use approximate distances. If you would like to use exact distances and buy a Google Maps license, please contact us.
A cheaper option would be to use the website’s distance feature to get a rough idea of which appraisers are closest to the address, and then switch to Google maps to refine your search by manually entering the addresses of two or three appraisers and the property.