Assessing the quality of education by economic output means the engineer who declines a job at Google or Facebook to take a job at a human rights non-profit is a "worse" engineer, and their education must be considered substandard compared to one who goes and takes a Big Tech job. Same with doctors who volunteer to run free HIV clinics in sub-Saharan Africa when they could get a job doing buttlifts for movie stars in Los Angeles, or lawyers who become public defenders or represent asylum seekers and other public interest clients rather than doing extremely well-compensated corporate work.
In as much as it reduces all of human life and values to numbers on a spreadsheet, yes, there is almost certainly something wrong with it.
First, it's obviously not a fair measure; tax contributed is not a direct reflection of education quality. Parents, background, accidents, moving abroad... You can't possibly clean the statistics enough to get rid of all those factors.
Second, it's not the business of the school to know my tax information and employment status. You can't measure something based on a number that you can't know.