Most regulatory agencies (safety and EMC) require certain printed documentation to be shipped with an amp and in specific languages. This is because much of the world still doesn’t have easy or reliable access to the internet, especially broad-band.
This goes along with specific labeling requirements for the product itself, such as FCC part 15B (for the US), safety and EMC marks (different for the different regions), specific labeling for input voltage, current/power, fuse data in a standardized format, manufacturer info, etc.
The labeling on the chassis, Declaration of Compliance and in the owner’s manual will in part determine compliance.