>>241466042True, it wasn't until the 80s which is funnily also why seminal western cyberpunk fiction brings up Japan, but it's not just Japan with copying, in general if a foreign thing was popular it was often easier to just make a domestic version, not just as a cheap alternative for global market.
Copyright law was and is sometimes messy, but some of these originals might not be patented, so not necessarily in breach of anything even if it is copying, or are simply homages.
For a curiosity I looked up the bidet, and indeed the invention was American, but it never took off there, and the inventor sold the rights of the patent to TOTO which then began production, making the Japanese product entirely legal and not even a case of copying someone. Thing didn't sell in America because apparently it was impossible to advertise at the time.