No, it's not, but again, a higher reward would make miners spend more on gear.
That's reasonable to assume it's true.
And that was back in March when we were below 200exa, we're now already at 220...
I think you're avoiding the big picture. Efficiency isn't just "which of the two requires more energy"; it's what's having a better performance. The banking system uses productive elements such as labor, buildings, cars, various kinds of tools, technology, energy of course etc., all of which could be used to satisfy another need. In Proof-of-Work there's no other real cost besides GPUs/ASICs and the energy that's required.
And again, transactions are settled more efficiently. It's more efficient to pay a merchant with Lightning. It's more efficient to send money oversea. It's more efficient to utilize divided possession.