I really doubt there is compression induced knocking related to octane in these cars. All modern motors are programmed to run just under the spark advance/fuel mixture that would cause knock- one knock from the sensors, and it backs off. This is the most efficient and powerful tune of any engine.
So to get the most horsepower the motor does need that higher octane. I run premium when I tow with my 2.0L because the horsepower for hill climbing and merging is a big deal then- despite the thirst it has with 3000 extra pounds.
When you see that you are 'throwing your money away" buying premium, it is more a comment that few drivers need that full power very often when putting around town or the highway. But when you truly demand the power it can be there.
Older cars had to be tuned with all sorts of compromises and assumptions, and the high compression/ large spark advance muscle car era demanded good juice all the time.
'15 Ingot Silver/ White Sands/ Reserve 2.0 FWD/CCD/ Tow Pkg/ Oct 14 2014
'55 F-100 and 64.5 Mustang Convertible