There's a contrarian theory presented by Robin that people go to highly reputable schools, visit highly reputable hospitals, buy highly reputable brands etc. to affiliate with high status individuals and institutions.
But what would a person who completely didn't care about such affiliations do? Pretty much the same thing. Unless you know a lot about schools, hospitals, and everything else, you're better off simply following prestige as proxy for quality (in addition to price and all the other usual criteria). There's no denying that prestige is better indicator of quality than random chance - the question is - is it the best we can do?
It's possible to come up with alternative measures, which might correlate with quality too, like operation success rates for hospitals, graduation rates for schools etc. But if they really indicated quality that well, wouldn't they be simply included in institution's prestige, and lose their predictive status? The argument is highly analogous to one for efficient market hypothesis (or to some extent with Bayesian beauty contest with schools, as prestige might indicate quality of other students). Very often there are severe faults with alternative measures, like with operation success rates without correcting for patient demographics.
If you postulate that you have better indicator of quality than prestige, you need to do some explaining. Why is it not included in prestige already? I don't propose any magical thinking about prestige, but we shouldn't be as eager to throw it away completely as some seem to be.
The second hypothesis would not be favored, even if the data turned out to be so.
As far as I know, nobody has done such tests, or at least no such test is in public knowledge. So obviously it couldn't have been incorporated in prestige yet.
When averaged over all human activities, it's not too hard to see that physically attractive people perform somewhat better. Incorporating it as part of default prestige mix makes sense when we don't know anything about real estate brokers.
If we suddenly came out with super-precise quality metrics for some field, it would turn out that prestige overestimates performance of some and underestimates performance of others. We just don't have any idea what would the adjustment be.
Well by your standards once one had collected such data one could see if it made any difference to new customers, when they were informed of it.