Earlier quoted context omitted.
> Imagine you didnt have law on shape and voltage of ordinsry power plugs in a house, and if you buy a samsung power socket to ibstall in your house, you mist buy samsung fridge and samsung washing machine and samsung hair dryer You seem to be conflating the wall socket with the on-device socket . I have several AC powered devices that use the same wall socket plug but have different on-device sockets - some with ver…
> You seem to be conflating the wall socket with the on-device socket. And the intent of the law is to bring the uniformity that exists in wall sockets to the on-device sockets.
1. There are currently several kinds of wall power voltages and plugs/receptacles commonly in use the US. Notable examples are the various 220-240V NEMA receptacles and the various 110-120V receptacles such as polarized 2-prong, unpolarized 2-prong, and 3-prong/grounded.
2. Although there are code requirements (e.g requiring that new outlets be grounded and polarized, or requiring ground fault protection in bathrooms) it doesn't appear that they mandate a particular plug or receptacle design (?) Though the NEMA (trade association) developed plugs can and do conform to the code requirements.
3. Power cords and on-device sockets aren't entirely standardized, but it's not nearly as big a deal as if there were dozens of 110-120V wall socket types rather than the three in common use.