Voltage is not the only thing that makes electricity dangerous. Static shocks are commonly around 5,000V, and most people don’t feel them if they are less than 2,000V. But they are only around 5mA. A standard North American house socket at 120V is 15A, so is capable of 1800W. The majority of 220-250V countries have 10A sockets for 2200-2500W. At those levels, there is no appreciable difference in the dangers imposed by sticking a fork in a socket.
If anything, the US ones are more dangerous if you live somewhere with switches on the sockets like here in Australia.