Ok put another way, rank the following (in your opinion) what's most important as a government:
1) ensuring domestic fuel production lines, protecting our gasoline supply in case of geopolitical instability in the middle east, venezuela or other oil producing countries. - this supports ethanol (corn or otherwise)
2) ensuring large scale factory corn producers are rich. -this supports corn ethanol and is unfortunately probably the biggest factor affecting govt prioritization of corn ethanol - corn has a powerful lobby, swings big volume of votes, and contributes large sums of money to politicians to favor their personal interests... Also means our taxes subsidize corn interests.
3) progressing toward greener fuel sources to begin to tackle the acute problem of local air pollution and the global problem or climate change. - this would support cellulosic ethanol instead of corn as a short term drop-in technology with lowest cost to bridge existing technology while the energy grid transitions to renewables for a shift to battery and hydrogen vehicles. Corn ethanol could help develop ethanol tech generally but for pure environmental gain, looking just at corn, it's basically a wash.
4) ensuring domestic food production of corn. We already produce more corn than we need and use it inefficiently to fill a bunch of other manufactured "needs" such as corn based sweetners etc; we don't really need to ensure farmland is used for corn food production, however this is an argument against corn ethanol.
5) negligible impact on cost of gasoline per mile, so the balance of cost and mpg and engine design etc, this as we've discussed also comes out a wash.
or 6) ensuring that your old mopeds have pliable rubber fuel lines for a longer period.
If you ranked all those and gave each a priority and value, and then factor in a bunch of guys paid you a lotta money and help ensure your cushy job if you vote in favor of corn ethanol, you can see how corn ethanol gets passed! democratic capitalism at it's finest