Substantial equivalency was never defined or enforced; they left us alone because our community was doing just fine – far better than most public schools, in terms of income and community stability.
Mentioning the strength of the community is also important, because it is clear evidence that chasidishe education isn’t “brutal, religious moral study” as they claim, but rather the sum of the experience – though totally different from the way goyim see education – is effective at producing productive, contributing members of society with stable families, good income, and lots of tax payers who fund the salaries of these hateful antisemites.