It's also kind of misleading. This map labels North America as 115-120V like everyone always does, when in fact it's ALSO a 240V system, it's just that the "common" plug and the "typical" circuit don't use it, they only use half of a center-tapped 240V line. So that's the "standard" they choose to use to label the whole system.

But it's kind of unfair. It's 240V coming into the house just like everywhere else in the world, except you also get the choice for it to be 120V. Being split-phase makes it easy to run multiple 120V circuits with a minimum of wire and still allows 240V for high-wattage appliances on their own dedicated circuits. It's actually a very clever system and basically every house is effectively supplied with both voltages. It's often poorly utilized, yes, with a few practical limitations and a lot of limitations due to historical conventions, but as a technical design it's really kind of the best of both worlds, and it could be utilized a lot more effectively than it is.

If I was allowed to have an outlet with two 120V sockets, and one 240V European-style socket, there's no technical reason I could not safely do that in a single outlet box. I could choose to plug in whatever I want at either voltage as long as it wasn't more than 15 amps. Of course code would never allow that, because we consider the higher voltage "more dangerous" but it's always right there, across two opposite phase 120V lines. We're just not allowed to use it, except for large electrical appliances like air conditioners and clothes dryers. It's frustrating.

Wow only 70 years ago