Happened to me when I saw a book on the US site, I wasn’t able to see all reviews, but there was a button to sort-of “apply” to get approved for seeing all of them.
It took five days, then I got this email.
Interestingly, they’re not doing this on the European site, you can still see all reviews there.
My favorite example is the Magnuson–Moss Warranty Act, which requires manufacturers to honor warranty on products that you or a third party have worked on in the past unless the manufacturer can prove that the specific malfunction for which you’re seeking warranty service was caused by the previous repair or modification.
Those “warranty void if removed” stickers are illegal.
It also prohibits manufacturers refusing to repair a product due to unrelated damage.