It already exists and is a free US Dept of Education service. Schools have to report that data to the Dept of Ed already, so they have both an interactive search tool [1] and the raw data available [2].

[1] https://collegescorecard.ed.gov/search/?page=0&sort=threshol...

[2] https://collegescorecard.ed.gov/data

Looking at [1] just now, it seems overwhelmingly oriented toward answering the question "How do I get in?". Scarcely at all toward "What can the school deliver to the student?" -- only relevant measure is Median Earnings.

The fine print:

>The median annual earnings of individuals that received federal student aid and began college at this institution 10 years ago, regardless of their completion status.

So for the anxious parent, not a lot to go on.

That seems naive to assume. We already live in a world where there are multiple rankings, and many of them (even some of the most important ones, like QS or Shanghai) rely only on independently collected or public data.

We already have what you suggested as a solution, and look at where we are. The problem is more fundamental.