It is obvious that no one really thought through the implications of transporters when they were created for TOS. Later, someone came up with the technology behind and it sounds horrific, but no one really understood the implications.
Even by TNG era, there was enough understanding of the idea of transporters where a species could have created a Moon like method of supplying labor, with workers being “beamed out” after their service and enough positions filled with different patterns enough to fool the crew.