Here is your missing nuance; AOPA spent much of that decade and the one prior lobbying against unleaded avgas. AOPA will claim in principle to support unleaded

Here is your missing nuance; AOPA spent much of that decade and the one prior lobbying against unleaded avgas. AOPA will claim in principle to support unleaded AvGas, but in reality GA pilots and their lobbyists have been opposed; each proposal was always considered too cumbersome or expensive to pilots...