Production line made both US and EU variants.
To save time and money on finding the right type of cord, outlets were ALL standard flat 110V Edison plugs, regardless of actual line voltage which could be switched(yes with a toggle switch) to 220V for testing of EU units.
Many times, when they switched from putting together 220V units back to US standard units, someone made the understandable mistake of plugging a 110V unit into the 220V power supply. A loud pop or two, and the smell of rancid fish oil let all know who had blown out the caps in the power supply again.