Silly you. Of course quality and condition are subjective. I think even USPAP addresses that. You cannot make a quality or condition determination without being subjective. However, trained eyes on a property is better than no eyes or untrained eyes. A trained appraiser is going to be better at estimating quality and condition than a algorithm. How does an algorithm account for the subjectives and or the intangibles? Ignore them? Pretend they don't exist? Thats not a good solution. Remember, someone inputs the data and parameters. Who is checking the data input and the veracity? Who is making sure there is no bias in the algorithms? There is room for bias in everything.
Actually you are wrong. They can be made very objective.
In simple terms if you have a good regression model on the tangible features, you get an estimated value for the tangible features. Subtract that from the sale price of the comparable and Voila! - you have the total value of all the other features not tangible, i.e. the intangible features. It is completely objective (on the comparable side).
You might ask, what good is the total value of the intangible features? Well, you can estimate the same total for the subject (which is the only thing that does require some subjective input) and subtract that from the value of the intangibles for the comparable, to get the total intangible adjustment for each of the comparables. That's a big difference, because one side of that equation for 6-12 comps, is completely objective and you only focus on estimating the value of the comparable for the subject --- through a specific procedure which minimizes error on that side [remember the regression model does give an estimate of the tangible features for the subject property as well].
Now, you might say, OK, you have an adjustment through this method for the total of all intangible features for all comps, but you still don't have the adjustments for specific intangible features. Well, it doesn't matter, because you can divide the total anyway you want between Quality, Condition, Functional Utility, ...., and it won't have any impact on the adjusted sales price for the comps. That's simple math. However, you do split the intangible sub-totals up, to explain to the user why the adjustments are why they are. And, you do this by studying of course the features of the sales comparables in relation to the subject. There is this underlying constraint, call it the "containment", all of your adjusted values of the intangible features have to total that sub-total you calculated. And if the the sales price was actually lower or higher than you thought it should have been, sorry about that!! This is a very tough constraint.
If you execute this method (IVCA: Intangible Value Containment Approach) correctly, you are guaranteed to pretty much have all adjusted sales prices within 1% of their average.
What can go wrong? Well, if you don't have a good regression model, you will likely find it difficult to split the sub-totals in a way that makes sense.
Here is an old demo, I actually have newer appraisals that are better, but this should do:
This is a heavily redacted report that was created using the Subjective Value Containment Approach
pvn.pub
Another way of putting this is that with IVCA, the Sale Price of the comparable comes first; while by the traditional approach, the appraiser first cooks up an adjustment for the comparable out of thin air (so to say). The IVCA is truly geared to actual Market Value, the Traditional SCA is geared to the appraiser's subjective imagination and is totally *** backwards.