In the US houses are supplied with 240V split phase. So most outlets are 120V from one of the two parts of the same phase. There are some outlets (e.g., for a d

In the US houses are supplied with 240V split phase. So most outlets are 120V from one of the two parts of the same phase. There are some outlets (e.g., for a drier) that use the whole 240V and with those getting high amps is also easy because US homes also usually have higher total power supplied than in Europe and they have standardized plugs that mean higher amps are available (without going to the industrial plugs we use in Europe). But if all you have is a pre-existing 120V outlet then it's very slow. So in more cases they need to do an upgrade but when they do the result is usually pretty good.