It's a common misconception that taxing authorities will have access to a client's appraisal. The only person with access to an appraisal is the client and anyone with whom the client willfully shares it. No one is entitled to the appraisal report without a client’s express written permission. It is confidential information.
Appraisers are bound by a uniform set of standards as to how appraisals are conducted and delivered, so there are built-in requirements to protect a client's privacy and to deliver the report securely. If you have questions about the process or the chain of data delivery from the appraiser to the client, this is something you should ask the appraiser to ensure an appraiser - you should get very clear information in response on how the standards are adhered to.