Possible.
I guess in the many many audits.. (we still do now know for sure how many ) this was never found. Mable he only gets audited by the feds..
New York City has its own special set of rules and regs. I don't know how it would work but I think someone in assessment would have had to go through the assessment rolls and determine whether each individual needed to submit their returns to prove income.
There are probably thousands of wealthy New Yorkers with this exemption still in place. I have no proof but it wouldn't surprise me in the least.