Microsoft, Sony, and others still use illegal warranty-void-if-removed stickers
Warranty-void-if-removed stickers reduce the cost to the company of providing the warranty, among other effects. Outlawing these stickers increases the cost of warranties to consumers who have no interest in opening the hardware. In this situation, it is unclear whether the use of government rule making -- and the use of government force to uphold those rules -- enhances overall welfare. I would be interested to hear from the regulators what assumptions were necessary to justify the policy.