It took Apple realizing that putting fashion so far out ahead of function on Vision Pro was costing it usage to see the dual strap. The ergonomics of the first strap were dog shit, and everyone, certainly Apple, knew years before Vision Pro launched that a dual strap was the only way to make longer sessions viable. But a dual strap was also uglier, and Vision Pro already had acceptability problems.
Look at the marketing materials for Vision Pro using the single strap. Next, look at the marketing materials with the dual strap. Which one of those would sell better into an office context where at least half the population spends considerable time fixing their hair. Which one looks slightly futuristic and which looks like a CPAP headset.
"How it looks" led Apple to ship a deficient strap, one that made the device actually hurt to use. And how it looks is why Apple stuck with that garbage strap for 18 months despite knowing from extensive user research that the dual strap was superior ergonomically, and despite having already done the R&D for the dual strap.
It was only when Apple had mostly given up on Vision Pro, understanding that the user base wasn't going to hockey stick, that fashion was already a complete failure, that they began offering the sillier looking but infinitely more functional dual strap. After 18 months, all Apple had was its existing user base, selling only a few thousand devices a month, so it shifted from growth to sustaining and that's what the dual strap and M5 logic board swap was for, holding onto the few users it has until it could figure out how or if to proceed with the product line.
That's not the case with Apple's headphones. That strap could easily be a lot higher quality without being a lot less fashionable.