It is indeed a protection against evil maid attacks as well as the industrialised version of shipment interception. It's probably also some form of PR and bran

It is indeed a protection against evil maid attacks as well as the industrialised version of shipment interception. It's probably also some form of PR and brand protection, and part of platform security as a whole. I doubt that any commercial company would find the side-effect of less end-user tampering a true downside; if the device says "I have been tampered with", that's a very clear signal that someone coming in for some warranty repair has some explaining to do.