I listened to the GIRO's podcast on the subject (althogh a bit dated); it is relatively still relevant and worth your listen if you want to dig deeper.
https://blisterreview.com/podcasts/ep-19-whats-next-the-future-of-helmet-design
some relevant timestamp markers:
Why MIPS matters, but why Giro wasn’t an early adopter (20:15)
Helmet Standards & Certifications: Who sets them & How does it all Work? (25:10)
What is Giro doing different or better than other helmet companies out there? Why should someone buy a Giro helmet? (50:19)
What’s the real difference between a $60 helmet and a $250 helmet? (59:15)
The engineers can't just design to an higher "standard", because nobody will buy it due to fit, appearance, and non-safety based performance compared to the other helmets on the market. So unfortunately the standard is set, and it's a race to balance that against the other purchase factors in order for it to be useful.
From a technical protection standpoint, there is only small percentage in the difference of protection; as long as the helmet is in the same parameters and physics of 1.5 inch of foam or whatever the depth is for the market standard helmet+shell.
In order to make a noticeable difference in safety requires orders of magnitude of difference like doubling the depth of the foam in of the helmet, like wearing a motorcyle helmet or a football helmet, or a double sized helmet.
The sad truth is nobody is going to buy or use the double-sized helmet when all the other helmets aren't that thick and cumbersome; so the engineers good efforts would help approximately zero customers.
So, all name-brand certified helmets, top-of-theline-to basic; you should consider to be within the same Tier from a protection perspective, unless we finally see some company come out with helmets that are physically much bigger and bulkier.
So I am not suprised that this article comes out to the conclusion that the cheap helmet beat the fancy wave helmet in protection; this is the same revelation that the GIRO engineer explained about 3years ago.
The minute percentage differences in protection you can fight about, but in practice are insignificant differences lost in the noise in the type of falls that occurs and how you score each one.
[I do think the wave helmet article above may take a bit of a clickbait pose in that the cheaper helmet "beats" the other thing, to be more intellectually honest, I would agree more with the GIRO engineer's categorizaton ALL the helmets are protection relatively "equally" in the same tier, and none are significantly better or worse. But that would mean all those star-ratings useless,]
The Giro engineer did indicate the bigger technologies such as MIPS; and perhaps the very new Koroyd have chances to be significantly different; but to be keen to not hop on to the latest thing, and really evaluate if it is different, or the physics are still the same that you can't do more without making the helmet bigger..
All this being said, having suffered a head injury with a helmet, don't expect it to be some kind of magic shield even if you get the fanciest helmet. Wearing a helmet doesn't have a significant downside during a fall and does possibly prevent worse damage, but it is like getting out of jail and rolling doubles in Monopoly. You only sometimes get out of it scott free; most of the time you're still going to get hurt.
It will also do absolutely nothing for your chin, mouth, teeth, tongue, eyes, nose etc, or rest of your body. it's not magic.
