Personally, while I'm not discounting all of what you say, I still think there's a large placebo effect in play, due to brand name, and that's specicically they bank on. I'll give two examples:
1. You buy a high quality fake designed to fool. The fake is so good, to you, it's now the same as the actual, so it doesnt matter.
2. Ultra expensive brands literally demand said prices due exclusively to brand. This isnt present in only sunglasses either. Two indentical T-shirts, one is brandless and sells for 10, the other merely has GAP sewn in... and it 3x the price solely due to that. I have a pair of sunglasses from Scarface that match the outrageously priced ones in the film 99%, literally. I've actually worn the "legit" brand from a friend and then my brandless, 10 dollar ones... and there's literally no difference whatsover. Not kidding. They are the same in color, size, and design. One goes for 10, the other for 3000... seriously, because it's just an ultra snooty brand.
Not saying the same of Olivier People, since I have no plans to ever wear any... most of their designs only look good on Pitt to me, but that same model I was referrng to, they themselves confirmed that pair offered no real protection and was just for fashion, yet the eplicas, being about 85ish% accurate DO have actual UV protection and the same look and tint, etc. In my mind, it's clear which SUNglasses I'd rather buy. Anyway, that was the OP523 model, not the one you were talking about. Just throwing in my two cents.
Excuse any typos... really hard writing this out on a glitchy cell phone. :-!