I was surprised to learn this. My Brazilian friend said you just had to know what outlets in the house where 110 and which were 220. If you got it wrong then the magic smoke came out.
Nothing wrong with the socket itself but the use for different voltages is terrifying.
I once saw a house in the US which had outlets that would accept either type, and you had to know if it was 120V or 240V. IIRC this was a type A socket, but it would accept either voltage.
(The standard US outlet "type B" is a NEMA 5-15)
The NEMA 6 series is wider than the 5 series and the 6-15P probably won't fit in those old outlets, but the NEMA 2-15P would. . . if you could find one.
(Using a different shape might be even better, to avoid plugging it wrong by accident or if it is dark and the label cannot be read or it is faded and cannot be read, etc, and you can more easily tell which device works with which plug because the shape matches the devices being plugged too.)
Multiple AC standards in 1 building is just dumb, period.
Almost all US houses have two voltages, but since the sockets are obviously incompatible it all works. I've seen industrial buildings that have more than one grid connection (and in one case they paid extra to ensure the grid connections went to different sub stations)