The government has no business assuming that the parents won't educate their children, therefore has no need for a "least intrusive" test.
If we don't assume basic good will and competency of most citizens, we assume a nation fit only for rule by an elite.
>>The government has no business assuming that the parents won't educate their children<<
For the sake of argument, what if the parents REFUSE to educate their children at all? Do they have that right as well? (I say yes.)