If this is the case, why don't we strip the scientifically illiterate of the right to vote, or perhaps give their votes a lower weight? Similarly, we could rejigger our immigration policies to raise the average level of scientific knowledge (e.g., deport all low skill immigrants, eliminate family reunification immigration, and give immigration preferences to engineers).

If our main purpose in increasing education is to improve the signal/noise ratio in the electoral process (rather than preparing people for more productive jobs), it seems far cheaper to reduce noise than to increase the signal.

Note: I'm not advocating this policy, I'm merely asking why it isn't a cheaper way to achieve the stated goal.