Comment by bitwize

https://www.youtube.com/watch?v=1skbgEGEn80

Why were old PCs beige? It turns out, Germany had workplace standards laws that mandated light, unobtrusive colors on office equipment. Because it was expensive to offer different SKUs for different regions, gray or beige PC cases became the only ones available worldwide.

If a jurisdiction as big or important as California passes a law mandating certain features on products available there, manufacturers may make those features part of their products worldwide to save on costs. OEMs may make bootloader-locked PCs which cannot run operating systems that don't do age check in order to comply with the law in California and Brazil, and decide it's not worth it to offer a bootloader-unlocked version.

If you think PC manufacturers are required to make bootloader-unlockable PCs, the only thing requiring them to do so is an edict from Microsoft, something they can and will reverse in order to comply with the law.