Somewhat simplified: As long as the feedback loop demands an injector duty cycle that is within predetermined limits, it can compensate for and run reasonably well on gas that burns relatively poorly (for whatever reason it does) by simply sending more fuel into the holes.
Conditions that produce pinging are further sought to be thwarted by using a knock sensor for additional feedback.
A Corolla has a lot of stuff going for it that can help deal with fuel variations and issues in ways that a majority of small engines are completely incapable of.
It tends to resolve to: Climb in, turn key, engine starts easily, and car drives fine -- just like it has done thousands of times before.
I drained the old fuel out and replaced with fresh, and it fired up on the first subsequent half-assed pull of the starter rope.
(Which reminds me: It's been six months again already. Time to see if it still works.)
You have to put in in the tank and run it for a bit to make sure that the carbs don't have untreated fuel inside.