Apples and oranges. You didnt pay for the “mock appraisals” the borrower did. Appraisals arent estimating market value they are justifying a loan based upon other comparable sales. At least the appraisers saw the house. They saw what was next door, they saw if there are powerlines overhead or a busy street behind it. They saw the condition of the property relative to the comps.
Zillow on the otherhand is trying to provide estimates of market value. It is very very misleading. I love that they provide legitimate data points but trying to estimate value is a step beyond what they should do. Sales history, recent sales etc all empower the consumer to ask good questions and evaluate market value. OTOH, Arbitrary estimates based upon inaccurate data serve no purpose.